Effect of magnesium sulfate administration on blood-brain barrier in a rat model of intraperitoneal sepsis: a randomized controlled experimental study

Sepsis-Exacerbated Brain Dysfunction After Intracerebral Hemorrhage

Sepsis susceptibility is significantly increased in patients with intracerebral hemorrhage (ICH), owing to immunosuppression and intestinal microbiota dysbiosis. To date, ICH with sepsis occurrence is still difficult for clinicians to deal with, and the mortality, as well as long-term cognitive disability, is still increasing. Actually, intracerebral hemorrhage and sepsis are mutually exacerbated via similar pathophysiological mechanisms, mainly consisting of systemic inflammation and circulatory dysfunction. The main consequence of these two processes is neural dysfunction and multiple organ damages, notably, via oxidative stress and neurotoxic mediation under the mediation of central nervous system activation and blood-brain barrier disruption. Besides, the comorbidity-induced multiple organ damages will produce numerous damage-associated molecular patterns and consequently exacerbate the severity of the disease. At present, the prospective views are about operating artificial restriction for the peripheral immune system and achieving cross-tolerance among organs via altering immune cell composition to reduce inflammatory damage.

Magnesium sulfate ameliorates sepsis-induced diaphragm dysfunction in rats via inhibiting HMGB1/TLR4/NF-κB pathway

Diaphragm dysfunction could be induced by sepsis with subsequent ventilatory pump failure that is associated with local infiltration of inflammatory factors in the diaphragm. It has been shown that the administration of anticonvulsant agent, magnesium sulfate (MgSO₄) could decrease systematic inflammatory response. We recently reported that MgSO₄ could inhibit macrophages high mobility group box 1 (HMGB1) secretion that confirms its anti-inflammatory properties. Toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signal pathway appears to be involved in the pathology of septic experimental animal’s inflammatory response and involve in the pathogenic mechanisms of sepsis-induced diaphragm dysfunction. Thus, in this study, we are aiming to explore whether MgSO₄ could ameliorate sepsis-induced diaphragm dysfunction via TLR4/NF-κB pathway in a rodent model with controlled mechanical ventilation (CMV) and subsequent septic challenge.

Induced normothermia ameliorates the procoagulant host response in human endotoxaemia

Background

Dysregulation of coagulation occurs commonly in sepsis, ranging from mild coagulopathy with decreased platelets to disseminated intravascular coagulation (DIC). We investigated the effect of induced normothermia on coagulation during lipopolysaccharide (LPS)-induced endotoxaemia in healthy volunteers.

Methods

Twelve volunteers received an infusion of bacterial lipopolysaccharide (Escherichia coli; 2 ng kg⁻¹) and were assigned to either induced normothermia or control. Induced normothermia to maintain core temperature at 37°C consisted of external surface cooling, cold i.v. fluids, and medication to reduce shivering (buspirone, clonidine, and magnesium sulphate). The primary outcome was the DIC score (International Society on Thrombosis and Haemostasis guideline). Prothrombin time (PT), activated partial thromboplastin time (aPTT), D-dimer, plasma von Willebrand factor (vWf), and rotational thromboelastometry (ROTEM) were measured before and 1, 3, 6, and 8 h after LPS infusion. Differences between groups were tested with a mixed effects model.

Results

In control subjects, lipopolysaccharide caused a fever, transiently decreased platelet levels and lowered activated partial thromboplastin time, while prolonging prothrombin time and increasing D-Dimer and vWf levels. Normothermia prevented the DIC-score exceeding 4, which occurred in 50% of control subjects. Normothermia also reduced the fall in platelet count by 67x10⁹ L⁻¹([95%CI:27-107]; p=0.002), aPTT (mean difference:3s [95%CI:1-5]; p=0.005) and lowered vWf levels by 89% ([95%CI:6-172]; p=0.03), compared to the fever group. ROTEM measurements were unaffected by lipopolysaccharide.

Conclusion

In human endotoxaemia, induced normothermia decreases markers of endothelial activation and DIC. Maintaining normothermia may reduce coagulopathy in hyperinflammatory states.

Basic physiology of the blood-brain barrier in health and disease: a brief overview

The blood-brain barrier (BBB), a dynamic interface between blood and brain constituted mainly by endothelial cells of brain microvessels, robustly restricts the entry of potentially harmful blood-sourced substances and cells into the brain, however, many therapeutically active agents concurrently cannot gain access into the brain at effective doses in the presence of an intact barrier. On the other hand, breakdown of BBB integrity may involve in the pathogenesis of various neurodegenerative diseases. Besides, certain diseases/disorders such as Alzheimer's disease, hypertension, and epilepsy are associated with varying degrees of BBB disruption. In this review, we aim to highlight the current knowledge on the cellular and molecular composition of the BBB with special emphasis on the major transport pathways across the barrier type endothelial cells. We further provide a discussion on the innovative brain drug delivery strategies in which the obstacle formed by BBB interferes with effective pharmacological treatment of neurodegenerative diseases/disorders.

Evaluation of Blood-Brain Barrier Integrity Using Vascular Permeability Markers: Evans Blue, Sodium Fluorescein, Albumin-Alexa Fluor Conjugates, and Horseradish Peroxidase

The blood-brain barrier (BBB) constituted by endothelial cells of brain microvessels is a dynamic interface, which controls and regulates the transport of various substances including peptides, proteins, ions, vitamins, hormones, and immune cells from the circulation into the brain parenchyma. Certain diseases/disorders such as Alzheimer's disease, sepsis, and hypertension can lead to varying degrees of BBB disruption. Moreover, impairment of BBB integrity has been implicated in the pathogenesis of various neurodegenerative diseases like epilepsy. In attempts to explore the wide spectrum of pathophysiologic mechanisms of these diseases/disorders, a variety of experimental insults targeted to the BBB integrity in vitro in cell culture models and in vivo in laboratory animals have been shown to alter BBB permeability causing enhanced transport of certain tracers such as sodium fluorescein, cadaverine-Alexa fluor, horseradish peroxidase, FITC-dextran, albumin-Alexa fluor conjugates, and Evans blue dye across the barrier. The permeability changes in barrier-type endothelial cells can be assessed by intravascular infusion of exogenous tracers and subsequent detection of the extravasated tracer in the brain tissue, which enable functional and structural analysis of BBB integrity. In this chapter, we aimed to highlight the current knowledge on the use of four most commonly performed tracers, namely, Evans blue, sodium fluorescein, albumin-Alexa fluor conjugates, and horseradish peroxidase. The experimental methodologies that we use in our laboratory for the detection of these tracers by macroscopy, spectrophotometry, spectrophotofluorometry, confocal laser scanning microscopy, and electron microscopy are also discussed. Tracing studies at the morphological level are mainly aimed at the identification of the tracers both in the barrier-related cells and brain parenchyma. In addition, BBB permeability to the tracers can be quantified using spectrophotometric and spectrophotofluorometric assays and image analysis by confocal laser scanning microscopy and electron microscopy. The results of our studies conducted under various experimental settings using the mentioned tracers indicate that barrier-type endothelial cells in brain microvessels orchestrate the paracellular and/or transcellular trafficking of substances across BBB. These efforts may not only contribute to designing approaches for the management of diseases/disorders associated with BBB breakdown but may also provide new insights for developing novel brain drug delivery strategies.

'Magnesium'-the master cation-as a drug-possibilities and evidences

Magnesium (Mg²⁺) is the 2nd most abundant intracellular cation, which participates in various enzymatic reactions; there by regulating vital biological functions. Magnesium (Mg²⁺) can regulate several cations, including sodium, potassium, and calcium; it consequently maintains physiological functions like impulse conduction, blood pressure, heart rhythm, and muscle contraction. But, it doesn't get much attention in account with its functions, making it a "Forgotten cation". Like other cations, maintenance of the normal physiological level of Mg²⁺ is important. Its deficiency is associated with various diseases, which point out to the importance of Mg²⁺ as a drug. The roles of Mg²⁺ such as natural calcium antagonist, glutamate NMDA receptor blocker, vasodilator, antioxidant and anti-inflammatory agent are responsible for its therapeutic benefits. Various salts of Mg²⁺ are currently in clinical use, but their application is limited. This review collates all the possible mechanisms behind the behavior of magnesium as a drug at different disease conditions with clinical shreds of evidence.

Headaches and Magnesium: Mechanisms, Bioavailability, Therapeutic Efficacy and Potential Advantage of Magnesium Pidolate

Magnesium deficiency may occur for several reasons, such as inadequate intake or increased gastrointestinal or renal loss. A large body of literature suggests a relationship between magnesium deficiency and mild and moderate tension-type headaches and migraines. A number of double-blind randomized placebo-controlled trials have shown that magnesium is efficacious in relieving headaches and have led to the recommendation of oral magnesium for headache relief in several national and international guidelines. Among several magnesium salts available to treat magnesium deficiency, magnesium pidolate may have high bioavailability and good penetration at the intracellular level. Here, we discuss the cellular and molecular effects of magnesium deficiency in the brain and the clinical evidence supporting the use of magnesium for the treatment of headaches and migraines.

CXCR2 antagonist attenuates neutrophil transmigration into brain in a murine model of LPS induced neuroinflammation

Sepsis-associated encephalopathy (SAE) is a devastating neurological complication of sepsis with intolerable high motility. SAE is accompanied with brain vascular injury, endothelial hyperpermeability, and neutrophil infiltration into the brain tissue, key inflammatory processes leading to further brain edema and neuronal cell apoptosis. Recent studies from us and others suggest that the chemokine receptor C-X-C Motif Chemokine Receptor 2 (CXCR2) is crucial for neutrophil recruitment during SAE. Here we use CXCR2 antagonist SB225002 to characterize the role of CXCR2 in brain infiltration of neutrophil in a murine model of SAE. Systemic administration of high-dose LPS (10 mg/kg) induced evident neutrophil infiltration into the cerebral cortex in wild-type mice. However, CXCR2 antagonist SB225002 markedly attenuated neutrophil infiltration into brain. The CXCR2 expression on neutrophils in the peripheral circulation was dramatically downregulated in response to this LPS dose, and endothelial CXCR2 was significantly upregulated, suggesting endothelial but not neutrophil CXCR2 plays a more important role in neutrophil infiltration into brain. Strikingly, although these CXCR2 antagonist SB225002 treated mice displayed reduced neutrophil infiltration, no change in neutrophil rolling and adhesion was observed. Furthermore, we confirmed that CXCR2 agonist CXCL1 induced a marked increase in actin stress fiber synthesis and paracellular gap formation in cultured cerebral endothelial cells, which is attenuated by SB225002. Thus, these results demonstrate a selective role for endothelial CXCR2 to regulate cerebral vascular permeability and neutrophil transmigration in high-dose LPS induced neuroinflammation, and also suggest a therapeutic potential of CXCR2 antagonist SB225002 in SAE.

L-3-n-butylphthalide attenuates inflammation response and brain edema in rat intracerebral hemorrhage model

L-3-n-butylphthalide(NBP), a compound found in Apium graveolens Linn seed extracts, has a therapeutic effect on acute ischemic stroke. The pathological inflammatory pathways and consequent brain edema in intracerebral hemorrhage (ICH) share some similar characteristics with ischemic stroke. We hypothesized that NBP has anti-inflammatory and therapeutic effects on rats with ICH. ICH was induced by an infusion of bacterial collagenase type IV into the unilateral striatum of anesthetized rats. The therapeutic effect of NBP was measured by assessing neurological function, brain water content, blood-brain barrier permeability, and expression of tumor necrosis factor-alpha (TNF-α) and matrix metalloproteinase-9 (MMP-9) around the hematoma 48 hours after surgery. Magnetic resonance imaging was performed 4 and 48 hours after ICH induction, and ICH-induced injured area volumes were measured using T2-weighted images. The NBP treatment group performed better in the neurological function test than the vehicle group. Moreover, in comparison with the vehicle group, NBP group showed a lower expanded hematoma volume, brain water content, blood-brain barrier permeability, and TNF-α/ MMP-9 expression level. Our results indicate that NBP attenuates inflammation and brain edema in rat ICH model. Therefore, our findings also provide a potential therapeutic strategy for the treatment of ICH with NBP.

Diagnosing acute brain dysfunction due to sepsis

Developments in the management of critically ill patients suffering organ dysfunctions have demonstrated that brain is the prominent organ to be effected during critical illness. Acute brain dysfunction due to pathologic neuroinflammatory processes associated with sepsis is commonly seen and related to morbidity and mortality in the ICU treatment. Studies reported that survivors of sepsis may suffer long-term cognitive dysfunction that affects quality of life. However, there are no specific approaches to diagnose acute brain dysfunction in the early phase to target protective measures. In recent years, imaging methods and biomarkers are the most important issues of studies. This review will address the current diagnostic approaches to acute brain dysfunction related to sepsis.

Therapeutic effects of curcumin on sepsis and mechanisms of action: A systematic review of preclinical studies

Sepsis is a complex disease that begins with an infectious disorder and causes excessive immune responses. Curcumin is considered as an active component of turmeric that can improve the condition in sepsis due to its anti-inflammatory and antioxidant properties. PubMed, Embase, Google Scholar, Web of Science, and Scopus databases were searched. Searching was not limited to a specific publication period. Only English-language original articles, which had examined the effect of curcumin on sepsis, were included. At first, 1,098 articles were totally found, and 209 articles were selected after excluding duplicated data; 46 articles were remained due to the curcumin effects on sepsis. These included 23 in vitro studies and 23 animal studies. Our results showed that curcumin and various analogs of curcumin can have an inhibitory effect on sepsis-induced complications. Curcumin has the ability to inhibit the inflammatory, oxidative coagulation factors, and regulation of immune responses in sepsis. Despite the promising evidence of the therapeutic effects of curcumin on the sepsis complication, further studies seem necessary to investigate its effect and possible mechanisms of action in human studies.

Magnesium sulfate protects blood-brain barrier integrity and reduces brain edema after acute ischemic stroke in rats

Brain edema is a fatal complication of acute ischemic stroke and associated with worse outcomes in patients. This study was designed to evaluate the effects of magnesium sulfate on vasogenic brain edema formation and blood-brain barrier (BBB) disruption caused by ischemia-reperfusion (IR) in a rat model of ischemic stroke. A total of 72 male Sprague-Dawley rats were categorized into the following three primary groups: sham, control ischemic, magnesium-sulfate-treated (300 mg/kg loading dose, followed by an additional 100 mg/kg) ischemic (n = 24 in each group). Transient focal cerebral ischemia was induced by 60-min-long occlusion of the left middle cerebral artery, followed by 24-h-long reperfusion. Sensorimotor deficits, infarct volume, and brain edema were evaluated at the end of the reperfusion period. The BBB permeability was assessed by Evans Blue extravasation technique. Lipid peroxidation levels were assessed by measuring the malondialdehyde content in the brain tissue homogenate, and the activities of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase were detected according to the technical manual of the assay kits. Induction of cerebral ischemia in the control group produced considerable BBB damage in conjunction with severe brain edema formation. Treatment with magnesium sulfate significantly attenuated brain edema and protected BBB integrity in the ischemic lesioned hemisphere. In addition, magnesium sulfate reduced lipid peroxidation and increased antioxidant protection of brain tissue by upregulating the activities of antioxidant enzymes. Treatment with magnesium sulfate protected BBB integrity against IR-induced damage and reduced vasogenic edema formation partly via antioxidant mechanisms in a rat model of acute ischemic stroke.

Magnesium sulfate attenuates brain edema by lowering AQP4 expression and inhibits glia-mediated neuroinflammation in a rodent model of eclampsia

Eclampsia is characterized by high morbidity and mortality wordwide. Magnesium sulfate (MgSO₄) is used frequently as a prophylaxis for eclamptic seizure in clinical settings. However, the underlying mechanism is less studied, we have previously demonstrated that MgSO₄ pretreatment decreases eclampsia-like seizure threshold. Here, we further evaluated the hypothesis that MgSO₄ exert neuroprotective actions in eclampsia-like rats model by ameliorating neuroinflammation and brain edema. In this study, the eclampsia-like model was established by administering lipopolysaccharide plus pentylenetetrazol in pregnant Sprague-Dawley rats. Rats were given MgSO₄ from gestation day14-19. Then, Iba-1 (a marker for microglia) and S100-B (a marker for astrocytes) expression levels in the hippocampus CA3 region were detected by Enzyme-linked immunosorbent assay. Cerebrospinal fluid (CSF) levels of inflammatory cytokines were measured by Luminex assays. Aquaporin-4 (a transmembrane water channel protein) expression levels in cortex were analyzed using immunohistochemistry. Astrocyte and microglia expressions were detected by immunofluorescence, neuronal damage were evaluated by Nissl staining, and changes in neuronal number in the hippocampal CA3 region (CA3) among different groups were detected by neuronal nuclei staining. Our results demonstrated that MgSO₄ effectively attenuated astrocyte and microglia activation and promoted the neuronal survival in the CA3. Additionally, MgSO₄ significantly reduced inflammatory cytokines response in the CSF, and decreased the expression of AQP-4 protein in the cortex. Collectively, the findings of this study indicated that MgSO₄ has a neuroprotective role in eclampsia-like seizure rats through its anti-neuroninflammatory and brain edema-attenuating properties.

Vitamin D administration, cognitive function, BBB permeability and neuroinflammatory factors in high-fat diet-induced obese rats

OBJECTIVES

The purpose of this research was to investigate the effects of vitamin D administration on cognitive function, nuclear factor-κB (NF-κB), brain-derived neurotrophic factor (BDNF) concentration in the hippocampus and blood-brain barrier (BBB) permeability in high-fat diet (HFD)-induced obese rats.

METHODS

Male Wistar rats were fed either a control diet or HFD for 16 weeks (n=20); then, each group was randomized into two subgroups supplemented orally with 500 IU kg^-1 vitamin D for 5 weeks. A Morris water maze (MWM) test was performed at the 21st week to examine cognitive function. BBB permeability was characterized by Evans blue dye in the hippocampus. BDNF and NF-κB concentrations in the hippocampus and serum vitamin D concentrations were also measured.

RESULTS

HFD led to a significant delay in escape latency time and reduced time of MWM probe test because of increased NF-κB and decreased BDNF concentrations in the hippocampus. Vitamin D supplementation in the HFD group significantly reduced body weight, NF-κB concentrations, BBB permeability and increased BDNF concentrations in the hippocampus.

CONCLUSIONS

Vitamin D reversed HFD-induced cognitive impairments by reduction of the NF-κB and elevation of BDNF concentrations and modulation of the BBB permeability in rats' hippocampus.

Magnesium Sulfate Prevents Placental Ischemia-Induced Increases in Brain Water Content and Cerebrospinal Fluid Cytokines in Pregnant Rats

Magnesium sulfate (MgSO₄) is the most widely used therapy in the clinic to prevent the progression of preeclampsia, a hypertensive disorder of pregnancy, to eclampsia. Eclampsia, manifested as unexplained seizures and/or coma during pregnancy or postpartum, accounts for ~13% of maternal deaths worldwide. While MgSO₄ continues to be used in the clinic, the mechanisms by which it exerts its protective actions are not well understood. In this study, we tested the hypothesis that MgSO₄ protects against placental ischemia-induced increases in brain water content and cerebrospinal fluid cytokines. To test this hypothesis, MgSO₄ was administered via mini-osmotic pump (60 mg/day, i.p.) to pregnant and placental ischemic rats, induced by mechanical reduction of uterine perfusion pressure, from gestational day 14–19. This treatment regimen of MgSO₄ led to therapeutic level of 2.8 ± 0.6 mmol/L Mg in plasma. MgSO₄ had no effect on improving placental ischemia-induced changes in mean arterial pressure, number of live fetuses, or fetal and placental weight. Placental ischemia increased, while MgSO₄ prevented the increase in water content in the anterior cerebrum. Cytokine and chemokine levels were measured in the cerebrospinal fluid using a multi-plex assay. Results demonstrate that cerebrospinal fluid, obtained via the cisterna magna, had reduced protein, albumin, interleukin (IL)-17A, IL-18, IL-2, eotaxin, fractalkine, interferon gamma, vascular endothelial growth factor (VEGF), and macrophage inflammatory protein (MIP)-2 following MgSO₄ treatment. These data support the hypothesis that MgSO₄ offers neuroprotection by preventing placental ischemia-induced cerebral edema and reducing levels of cytokines/chemokines in the cerebrospinal fluid.

Sugammadex-Enhanced Neuronal Apoptosis following Neonatal Sevoflurane Exposure in Mice

In rodents, neonatal sevoflurane exposure induces neonatal apoptosis in the brain and results in learning deficits. Sugammadex is a new selective neuromuscular blockade (NMB) binding agent that anesthesiologists can use to achieve immediate reversal of an NMB with few side effects. Given its molecular weight of 2178, sugammadex is thought to be unable to pass through the blood brain barrier (BBB). Volatile anesthetics can influence BBB opening and integrity. Therefore, we investigated whether the intraperitoneal administration of sugammadex could exacerbate neuronal damage following neonatal 2% sevoflurane exposure via changes in BBB integrity. Cleaved caspase-3 immunoblotting was used to detect apoptosis, and the ultrastructure of the BBB was examined by transmission electron microscopy. Exposure to 2% sevoflurane for 6 h resulted in BBB ultrastructural abnormalities in the hippocampus of neonatal mice. Sugammadex alone without sevoflurane did not induce apoptosis. The coadministration of sugammadex with sevoflurane to neonatal mice caused a significant increase (150%) in neuroapoptosis in the brain compared with 2% sevoflurane. In neonatal anesthesia, sugammadex could influence neurotoxicity together with sevoflurane. Exposure to 2% sevoflurane for 6 h resulted in BBB ultrastructural abnormalities in the hippocampus of neonatal mice.

Effect of magnesium sulfate and thyroxine on inflammatory markers in a rat model of hypothyroidism

Inflammation is a major risk factor for cardiovascular complications. Magnesium sulfate (MgSO4) has anti-inflammatory actions. Therefore we investigated the effects of levothyroxine and MgSO4 on inflammatory markers as C-reactive protein (CRP), interleukin-6, tumor necrosis factor-α (TNF-α), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in hypothyroid rats. Sixty male rats were divided into 6 groups; normal, normal + MgSO4, hypothyroidism, hypothyroidism + levothyroxine, hypothyroidism + MgSO4, and hypothyroidism + levothyroxine + MgSO4. Thyroxine, triiodothyronine, and thyroid-stimulating hormone (TSH), CRP, interleukin-6, TNF-α, ICAM-1, and VCAM-1 were measured in all rats. Hypothyroidism significantly increased TSH, CRP, interleukin-6, TNF-α, ICAM-1, and VCAM-1 and decreased triiodothronine and thyroxine. Treatment of hypothyroid rats with levothyroxine or MgSO4 significantly decreased CRP, interleukin-6, TNF-α, ICAM-1, and VCAM-1. Combined therapy of hypothyroid rats with levothyroxine and MgSO4 significantly decreased CRP, interleukin-6, TNF-α, ICAM-1, and VCAM-1 compared with hypothyroid rats either untreated or treated with levothyroxine or MgSO4. This study demonstrates that hypothyroid rats have chronic low grade inflammation, which may account for increased risk of cardiovascular diseases. Combined levothyroxine and MgSO4 is better than levothyroxine or MgSO4 alone in alleviating the chronic low grade inflammatory status and therefore reducing the risk of cardiovascular diseases in hypothyroid animals.

Hypomagnesemia in Critically Ill Sepsis Patients

Magnesium (Mg), also known as “the forgotten electrolyte”, is the fourth most abundant cation overall and the second most abundant intracellular cation in the body. Mg deficiency has been implicated in the pathophysiology of many diseases. This article is a review of the literature regarding Mg abnormalities with emphasis on the implications of hypomagnesemia in critical illness and on treatment options for hypomagnesemia in critically ill patients with sepsis. Hypomagnesemia is common in critically ill patients, and there is strong, consistent clinical evidence, largely from observational studies, showing that hypomagnesemia is significantly associated with increased need for mechanical ventilation, prolonged ICU stay and increased mortality. Although the mechanism linking hypomagnesemia with poor clinical outcomes is not known, experimental data suggest mechanisms contributing to such outcomes. However, at the present time, there is no clear evidence that magnesium supplementation improves outcomes in critically ill patients with hypomagnesemia. Large, well-designed clinical trials are needed to evaluate the role of magnesium therapy for improving outcomes in critically ill patients with sepsis.

Therapeutic effects of human urocortin-1, -2 and -3 in intracerebral hemorrhage of rats

Urocortin exerts neuroprotective effects in intracerebral hemorrhage (ICH) of rats. For pre-clinical trial, we intended to study the neuroprotective efficacy of human UCN (hUCN)-1, -2 and -3 in treating ICH rats. ICH was induced by infusing bacterial collagenase VII (0.23 U in sterile saline) to the striatum. The hUCN-1, -2, and -3 were administrated (2.5μg/kg, i.p.) at 1h after ICH insult, respectively. Neurological deficits were evaluated by modified Neurological Severity Scores. Brain edema and hematoma expansion was evaluated by coronal T2-WI and DWI magnetic resonance imaging on 1, 3, 6, 24, and 56h after ICH insult. Blood-brain barrier permeability was evaluated by Evans blue assay on day 3 after ICH. Brain lesion volume was evaluated by morphormetric measurement on day 7 after ICH. Our results demonstrated that the hUCN-1 significantly reduced hematoma, blood-brain barrier disruption and neurological deficits on day 3, and brain lesion volume on day 7 after ICH insult. The prediction of secondary structure of the hUCNs clarifies that the percentage of alpha-helix, random coil and extended strand between rat-UCN (rUCN)-1 and hUCN-1 are the same. The structure similarity between human- and rat-UCN-1 may be one of the reasons that both can exert similar therapeutic potential in ICH rats.

Pretreatment with magnesium ameliorates lipopolysaccharide-induced liver injury in mice

BACKGROUND

Lipopolysaccharide (LPS), a component of the outer membrane of Gram-negative bacteria, is involved in the pathogenesis of sepsis. LPS administration induces systemic inflammation that mimics many of the initial clinical features of sepsis and has deleterious effects on several organs including the liver and eventually leading to septic shock and death. The present study aimed to investigate the protective effect of magnesium (Mg), a well known cofactor in many enzymatic reactions and a critical component of the antioxidant system, on hepatic damage associated with LPS-induced endotoxima in mice.

METHODS

Mg (20 and 40mg/kg, po) was administered for 7 consecutive days. Systemic inflammation was induced 1h after the last dose of Mg by a single dose of LPS (2mg/kg, ip) and 3h thereafter plasma was separated, animals were sacrificed and their livers were isolated.

RESULTS

LPS-treated mice suffered from hepatic dysfunction revealed by histological observation, elevation in plasma transaminases activities, C-reactive protein content and caspase-3, a critical marker of apoptosis. Liver inflammation was evident by elevation in liver cytokines contents (TNF-α and IL-10) and MPO activity. Additionally, oxidative stress was manifested by increased liver lipoperoxidation, glutathione depletion, elevated total nitrate/nitrite (NOx) content and glutathione peroxidase (GPx) activity. Pretreatment with Mg largely mitigated these alternations.

CONCLUSION

Pretreatment with Mg protects the liver from the acute injury which occurs shortly after septicemia.

Caecal ligation and puncture induced sepsis in the rat results in increased brain water content and perimicrovessel oedema

To investigate brain water content and ultrastructure in a rat caecal ligation and puncture (CLP) model of sepsis, adult male Wistar rats were assigned to one of the following experimental groups: CLP, Un-operated or Sham. CLP was performed under anaesthesia, Sham rats were exposed to anaesthesia, laparotomy and caecal mobilisation and Un-operated rats did not experience anaesthesia or surgery. CLP and Sham rats were sacrificed 18-20 h following recovery from surgery and Un-operated rats were sacrificed at the same time. Frontal cortex samples (CLP n = 9; Un-operated n = 10; Sham n = 8) were taken immediately post mortem and their water content determined using gravimetry. Similar samples were taken from other rats (CLP n = 8; Un-operated n = 8; Sham n = 8), processed for electron microscopy and subjected to morphometric analysis. There was significantly more brain water in CLP than Un-operated (P < 0.01) and Sham (P < 0.05) rats. Electron microscopy revealed significantly more peri-microvessel oedema in CLP than Un-operated (P < 0.001) and Sham rats (P < 0.05). Microvessel endothelial cell lumen cross-sectional area was significantly smaller in CLP than Un-operated (P < 0.001) and Sham (P < 0.05) rats and microvessel endothelial cell cross-sectional area was significantly smaller in CLP than Un-operated (P < 0.05) rats. Significantly more endothelial cell cytoplasmic area was occupied by mitochondria in CLP than Un-operated (P < 0.05) and Sham (P < 0.05) rats. However, experimental group did not affect the number of mitochondria present in endothelial cell profiles, or their cross-sectional area. Therefore, sepsis-induced cerebral oedema involves an increase in and a redistribution of brain water, together with ultrastructural changes to cerebral microvessels and adjacent tissue.

The pro-inflammatory cytokine interferon-gamma is an important driver of neuropathology and behavioural sequelae in experimental pneumococcal meningitis

Interferon-gamma is known to play a complex modulatory role in immune defence during microbial infections. Its actions in pneumococcal meningitis, however, remain ill-defined. Here, a pathological role for IFN-γ was demonstrated using a murine model of pneumococcal meningitis, in that C57BL/6J mice deficient in this pro-inflammatory cytokine (IFN-γ(-/-)) showed less severe acute and long-term neuropathology following intracerebral challenge with Streptococcus pneumoniae. The absence of IFN-γ significantly lengthened the survival of mice that otherwise would have developed fatal clinical signs within two days of CNS infection. Compared to their wild-type counterparts, IFN-γ(-/-) mice showed a diminished inflammatory response (attenuated levels of pro-inflammatory cytokines in the cerebrospinal fluid) and milder brain pathologies (less BBB permeability to protein and brain haemorrhage) during the acute phase of disease. Following a full regime of antibiotic treatment, we found substantial brain injuries in the wild-type mice 10days after infection. IFN-γ(-/-) mice, however, showed decreased neuronal damage in both hippocampus and cortex. In the longer term (≈10weeks p.i.), the wild-type mice that had survived meningitis due to antibiotic treatment had neurobehavioural abnormalities including diurnal hypoactivity, nocturnal hyperactivity and impaired performance in a discrimination reversal task. IFN-γ(-/-) mice, concomitantly tested in the automated IntelliCage platform, had reduced behavioural and cognitive disorders compared to wild-type mice. Both IFN-γ(-/-) and wild-type survivors of pneumococcal meningitis showed impaired working memory in the IntelliCage-based complex patrolling task. These observations indicate an association between IFN-γ-driven acute brain pathology and the long-term neurological sequelae resulting from pneumococcal meningitis.

MRI reveals edema in larynx (but not in brain) during anaphylactic hypotension in anesthetized rats

Purpose

Anaphylactic shock is sometimes accompanied by local interstitial edema due to increased vascular permeability. We performed magnetic resonance imaging (MRI) to compare edema in the larynx and brain of anesthetized rats during anaphylactic hypotension versus vasodilator-induced hypotension.

Methods

Male Sprague Dawley rats were subjected to hypotension induced by the ovalbumin antigen (n=7) or a vasodilator sodium nitroprusside (SNP; n=7). Apparent diffusion coefficient (ADC) and T2-relaxation time (T2RT) were quantified on MRI performed repeatedly for up to 68 min after the injection of either agent. The presence of laryngeal edema was also examined by histological examination. Separately, the occurrence of brain edema was assessed by measuring brain water content using the wet/dry method in rats with anaphylaxis (n=5) or SNP (n=5) and the non-hypotensive control rats (n=5). Mast cells in hypothalamus were morphologically examined.

Results

Mean arterial blood pressure similarly decreased to 35 mmHg after an injection of the antigen or SNP. Hyperintensity on T2-weighted images (as reflected by elevated T2RT) was found in the larynx as early as 13 min after an injection of the antigen, but not SNP. A postmortem histological examination revealed epiglottic edema in the rats with anaphylaxis, but not SNP. In contrast, no significant changes in T2RT or ADC were detectable in the brains of any rats studied. In separate experiments, the quantified brain water content did not increase in either anaphylaxis or SNP rats, as compared with the non-hypotensive control rats. The numbers of mast cells with metachromatic granules in the hypothalamus were not different between rats with anaphylaxis and SNP, suggesting the absence of anaphylactic reaction in hypothalamus.

Conclusion

Edema was detected using the MRI technique in the larynx during rat anaphylaxis, but not in the brain.

Sepsis-induced brain dysfunction

Systemic infection is often revealed by or associated with brain dysfunction, which is characterized by alteration of consciousness, ranging from delirium to coma, seizure or focal neurological signs. Its pathophysiology involves an ischemic process, secondary to impairment of cerebral perfusion and its determinants and a neuroinflammatory process that includes endothelial activation, alteration of the blood-brain barrier and passage of neurotoxic mediators. Microcirculatory dysfunction is common to these two processes. This brain dysfunction is associated with increased mortality, morbidity and long-term cognitive disability. Its diagnosis relies essentially on neurological examination that can lead to specific investigations, including electrophysiological testing or neuroimaging. In practice, cerebrospinal fluid analysis is indisputably required when meningitis is suspected. Hepatic, uremic or respiratory encephalopathy, metabolic disturbances, drug overdose, sedative or opioid withdrawal, alcohol withdrawal delirium or Wernicke's encephalopathy are the main differential diagnoses. Currently, treatment consists mainly of controlling sepsis. The effects of insulin therapy and steroids need to be assessed. Various drugs acting on sepsis-induced blood-brain barrier dysfunction, brain oxidative stress and inflammation have been tested in septic animals but not yet in patients.

Understanding brain dysfunction in sepsis

Sepsis often is characterized by an acute brain dysfunction, which is associated with increased morbidity and mortality. Its pathophysiology is highly complex, resulting from both inflammatory and noninflammatory processes, which may induce significant alterations in vulnerable areas of the brain. Important mechanisms include excessive microglial activation, impaired cerebral perfusion, blood-brain-barrier dysfunction, and altered neurotransmission. Systemic insults, such as prolonged inflammation, severe hypoxemia, and persistent hyperglycemia also may contribute to aggravate sepsis-induced brain dysfunction or injury. The diagnosis of brain dysfunction in sepsis relies essentially on neurological examination and neurological tests, such as EEG and neuroimaging. A brain MRI should be considered in case of persistent brain dysfunction after control of sepsis and exclusion of major confounding factors. Recent MRI studies suggest that septic shock can be associated with acute cerebrovascular lesions and white matter abnormalities. Currently, the management of brain dysfunction mainly consists of control of sepsis and prevention of all aggravating factors, including metabolic disturbances, drug overdoses, anticholinergic medications, withdrawal syndromes, and Wernicke's encephalopathy. Modulation of microglial activation, prevention of blood-brain-barrier alterations, and use of antioxidants represent relevant therapeutic targets that may impact significantly on neurologic outcomes. In the future, investigations in patients with sepsis should be undertaken to reduce the duration of brain dysfunction and to study the impact of this reduction on important health outcomes, including functional and cognitive status in survivors.

Sufficient virus-neutralizing antibody in the central nerve system improves the survival of rabid rats

Background

Rabies is known to be lethal in human. Treatment with passive immunity for the rabies is effective only when the patients have not shown the central nerve system (CNS) signs. The blood–brain barrier (BBB) is a complex functional barrier that may compromise the therapeutic development in neurological diseases. The goal of this study is to determine the change of BBB integrity and to assess the therapeutic possibility of enhancing BBB permeability combined with passive immunity in the late stage of rabies virus infection.

Methods

The integrity of BBB permeability in rats was measured by quantitative ELISA for total IgG and albumin levels in the cerebrospinal fluid (CSF) and by exogenously applying Evans blue as a tracer. Western blotting of occludin and ZO-1, two tight junction proteins, was used to assess the molecular change of BBB structure.

The breakdown of BBB with hypertonic arabinose, recombinant tumor necrosis factor-alpha (rTNF-γ), and focused ultrasound (FUS) were used to compare the extent of BBB disruption with rabies virus infection. Specific humoral immunity was analyzed by immunofluorescent assay and rapid fluorescent focus inhibition test. Virus-neutralizing monoclonal antibody (mAb) 8-10E was administered to rats with hypertonic breakdown of BBB as a passive immunotherapy to prevent the death from rabies.

Results

The BBB permeability was altered on day 7 post-infection. Increased BBB permeability induced by rabies virus infection was observed primarily in the cerebellum and spinal cord. Occludin was significantly decreased in both the cerebral cortex and cerebellum. The rabies virus-specific antibody was not strongly elicited even in the presence of clinical signs. Disruption of BBB had no direct association with the lethal outcome of rabies. Passive immunotherapy with virus-neutralizing mAb 8-10E with the hypertonic breakdown of BBB prolonged the survival of rabies virus-infected rats.

Conclusions

We demonstrated that the BBB permeability was altered in a rat model with rabies virus inoculation. Delivery of neutralizing mAb to the infected site in brain combined with effective breakdown of BBB could be an aggressive but feasible therapeutic mode in rabies when the CNS infection has been established.

Adiponectin-deficiency exaggerates sepsis-induced microvascular dysfunction in the mouse brain

Obesity increases circulating cell-endothelial cell interactions; an early marker of inflammation in laboratory model of sepsis, but little is known about the effect of different adipokines. Adiponectin is an anti-inflammatory adipokine secreted by adipocytes. Adiponectin deficiency is implicated in exaggerated proinflammatory phenotype in both obesity and sepsis via increased proinflammatory cytokine expression. However the effect of adiponectin deficiency on circulating cell-endothelial cell interactions in polymicrobial sepsis is unknown. Furthermore although brain dysfunction in septic patients is a known predictor of death, the pathophysiology involved is unknown. In the current study, we examined the effects of adiponectin deficiency on leukocyte (LA) and platelet adhesion (PA) in cerebral microcirculation of septic mice. Adiponectin deficient (Adipoq(-/-): Adko) and background strain C57Bl/6 (wild type (WT)) mice were used. Sepsis was induced using cecal ligation and puncture (CLP). We studied LA and PA in the cerebral microcirculation using intravital fluorescent video microscopy (IVM), blood brain barrier (BBB) dysfunction using Evans Blue (EB) leakage method and E-selectin expression using dual radiolabeling technique in different WT and Adko mice with CLP. Adiponectin deficiency significantly exaggerated LA (WT-CLP:201 ± 17; Adko-CLP: ± 53 cells/mm(2); P < 0.05) and PA (WT-CLP:125 ± 17; Adko-CLP:188 ± 20 cells/mm(2); P < 0.05) in cerebral microcirculation, EB leakage (WT-CLP:10 ± 3.7; Adko-CLP:24 ± 4.3 ng/g × µl plasma; P < 0.05) and E-selectin expression (WT-CLP:0.06 ± 0.11; Adko-CLP:0.44 ± 0.053 ng/g; P < 0.05) in the brain tissue of the mice with CLP. Furthermore, E-selectin monoclonal antibody (mAb) treatment attenuated cell adhesion and BBB dysfunction of Adko-CLP mice. Adiponectin deficiency is associated with exaggerated leukocyte and PA in cerebral microcirculation of mice with CLP via modulation of E-selectin expression.

Systemic administration of urocortin after intracerebral hemorrhage reduces neurological deficits and neuroinflammation in rats

Background

Intracerebral hemorrhage (ICH) remains a serious clinical problem lacking effective treatment. Urocortin (UCN), a novel anti-inflammatory neuropeptide, protects injured cardiomyocytes and dopaminergic neurons. Our preliminary studies indicate UCN alleviates ICH-induced brain injury when administered intracerebroventricularly (ICV). The present study examines the therapeutic effect of UCN on ICH-induced neurological deficits and neuroinflammation when administered by the more convenient intraperitoneal (i.p.) route.

Methods

ICH was induced in male Sprague-Dawley rats by intrastriatal infusion of bacterial collagenase VII-S or autologous blood. UCN (2.5 or 25 μg/kg) was administered i.p. at 60 minutes post-ICH. Penetration of i.p. administered fluorescently labeled UCN into the striatum was examined by fluorescence microscopy. Neurological deficits were evaluated by modified neurological severity score (mNSS). Brain edema was assessed using the dry/wet method. Blood-brain barrier (BBB) disruption was assessed using the Evans blue assay. Hemorrhagic volume and lesion volume were assessed by Drabkin's method and morphometric assay, respectively. Pro-inflammatory cytokine (TNF-α, IL-1β, and IL-6) expression was evaluated by enzyme-linked immunosorbent assay (ELISA). Microglial activation and neuronal loss were evaluated by immunohistochemistry.

Results

Administration of UCN reduced neurological deficits from 1 to 7 days post-ICH. Surprisingly, although a higher dose (25 μg/kg, i.p.) also reduced the functional deficits associated with ICH, it is significantly less effective than the lower dose (2.5 μg/kg, i.p.). Beneficial results with the low dose of UCN included a reduction in neurological deficits from 1 to 7 days post-ICH, as well as a reduction in brain edema, BBB disruption, lesion volume, microglial activation and neuronal loss 3 days post-ICH, and suppression of TNF-α, IL-1β, and IL-6 production 1, 3 and 7 days post-ICH.

Conclusion

Systemic post-ICH treatment with UCN reduces striatal injury and neurological deficits, likely via suppression of microglial activation and inflammatory cytokine production. The low dose of UCN necessary and the clinically amenable peripheral route make UCN a potential candidate for development into a clinical treatment regimen.

Sepsis-associated encephalopathy

Sepsis-associated encephalopathy (SAE) is defined as a diffuse or multifocal cerebral dysfunction induced by the systemic response to the infection without clinical or laboratory evidence of direct brain infection. Its pathogenesis is multifactorial. SAE generally occurs early during severe sepsis and precedes multiple-organ failure. The most common clinical feature of SAE is the consciousness alteration which ranges from mildly reduced awareness to unresponsiveness and coma. Diagnosis of SAE is primarily clinical and depends on the exclusion of other possible causes of brain deterioration. Electroencephalography (EEG) is almost sensitive, but it is not specific for SAE. Computed Tomography (CT) head scan generally is negative in case of SAE, while Magnetic Resonance Imaging (MRI) can show brain abnormalities in case of SAE, but they are not specific for this condition. Somatosensitive Evoked Potentials (SEPs) are sensitive markers of developing cerebral dysfunction in sepsis. Cerebrospinal fluid (CBF) analysis is generally normal, a part an inconstant elevation of proteins concentration. S100B and NSE have been proposed like biomarkers for diagnosis of SAE, but the existing data are controversial. SAE is reversible even if survivors of severe sepsis have often long lasting or irreversible cognitive and behavioral sequel; however the presence of SAE can have a negative influence on survival. A specific therapy of SAE does not exist and the outcome depends on a prompt and appropriate treatment of sepsis as whole.

Therapeutic benefit of urocortin in rats with intracerebral hemorrhage

Object

Intracerebral hemorrhage (ICH) accounts for about 15% of all deaths due to stroke. It frequently causes brain edema, leading to an expansion of brain volume that exerts a negative impact on ICH outcomes. The ICH-induced brain edema involves inflammatory mechanisms. The authors' in vitro study shows that urocortin (UCN) exhibits antiinflammatory and neuroprotective effects. Therefore, the neuroprotective effect of UCN on ICH in rats was investigated.

Methods

Intracerebral hemorrhage was induced by an infusion of bacteria collagenase type VII-S or autologous blood into the unilateral striatum of anesthetized rats. At 1 hour after the induction of ICH, UCN (0.05, 0.5, and 5 μg) was infused into the lateral ventricle on the ipsilateral side. The authors examined the injury area, brain water content, blood-brain barrier permeability, and neurological function.

Results

The UCN, administered in the ipsilateral lateral ventricle, was able to penetrate into the injured striatum. Posttreatment with UCN reduced the injury area, brain edema, and blood-brain barrier permeability and improved neurological deficits of rats with ICH.

Conclusions

Posttreatment with UCN through improving neurological deficits of rats with ICH dose dependently provided a potential therapeutic agent for patients with ICH or other brain injuries.

Disturbances of the hypothalamic-pituitary-adrenal axis and plasma electrolytes during experimental sepsis

Background

Sepsis continues to be a poorly understood syndrome with a high mortality rate. While we are beginning to decipher the intricate interplay of the inflammatory response during sepsis, the precise regulation of the hypothalamic-pituitary-adrenal (HPA) axis and its impact on electrolyte homeostasis during sepsis remains incompletely understood.

Methods

Sepsis was induced in adult male Sprague-Dawley rats by cecal ligation and puncture (CLP). Plasma samples were obtained as a function of time (6-48 hrs) after CLP and compared with healthy animals (neg ctrl). Samples were analyzed for adrenocorticotropin (ACTH), corticosterone, and aldosterone levels, as well as concentrations of sodium (Na⁺), potassium (K⁺), chloride (Cl^-), and magnesium (Mg²⁺).

Results

ACTH levels were found to be significantly reduced 6-24 hrs after CLP in comparison to baseline levels and displayed gradual recovery during the later course (24-48 hrs) of sepsis. Plasma corticosterone concentrations exhibited a bell-shaped response, peaking between 6 and 12 hrs followed by rapid decline and concentrations below negative control levels 48 hrs after injury. Aldosterone levels in septic animals were continuously elevated between 6 and 48 hrs. Whereas plasma Na⁺ levels were found to be persistently elevated following CLP, levels of K⁺, Cl^- and Mg²⁺ were significantly reduced as a function of time and gradually recovered during the later course of sepsis.

Conclusions

CLP-induced sepsis resulted in dynamic changes of ACTH, corticosterone, and aldosterone levels. In addition, electrolyte levels showed significant disturbances after CLP. These electrolyte perturbations might be evoked by a downstream effect or a dysfunctional HPA-axis response during sepsis and contribute to severe complications during sepsis.

Magnesium sulfate mitigates acute lung injury in endotoxemia rats

BACKGROUND

Magnesium sulfate (MgSO4) possesses potent anti-inflammation capacity. We sought to elucidate the effects of MgSO4 on mitigating acute lung injury induced by endotoxemia. MgSO4 is an antagonist of the L-type calcium channels and the N-methyl-D-aspartate (NMDA) receptor. The roles of the L-type calcium channels and NMDA receptor in this regard were also elucidated.

METHODS

Ninety-six adult male rats were randomized to receive normal saline, MgSO4 (100 mg/kg), lipopolysaccharide (LPS), LPS plus MgSO4 (10, 50, or 100 mg/kg), LPS plus MgSO4 (100 mg/kg) plus the L-type calcium channel activator BAY-K8644, or LPS plus MgSO4 (100 mg/kg) plus exogenous NMDA (n=12 in each group). Between-group differences in lung injury were evaluated.

RESULTS

Histologic findings, in concert with assays of leukocyte infiltration (polymorphonuclear leukocytes/alveoli ratio and myeloperoxidase activity) and lung water content (wet/dry weight ratio), confirmed that LPS induced acute lung injury. LPS also caused significant inflammatory response (increases in chemokine, cytokine, and prostaglandin E2 concentrations) and imposed significant oxidative stress (increases in nitric oxide and malondialdehyde concentrations) in rat lungs. MgSO4 at the dosages of 50 mg/kg and 100 mg/kg, but not at 10 mg/kg, significantly mitigated the acute lung injury, lung inflammatory response, and oxidative stress caused by endotoxemia. Moreover, the protective effects of MgSO4 were counteracted by BAY-K8644 and exogenous NMDA.

CONCLUSIONS

MgSO4 mitigates lung inflammatory response, oxidative stress, and acute lung injury in endotoxemia rats in a dose-dependent manner. The mechanisms may involve antagonizing the L-type calcium channels and the NMDA receptor.

Neuro-oxidative-nitrosative stress in sepsis

Neuro-oxidative-nitrosative stress may prove the molecular basis underlying brain dysfunction in sepsis. In the current review, we describe how sepsis-induced reactive oxygen and nitrogen species (ROS/RNS) trigger lipid peroxidation chain reactions throughout the cerebrovasculature and surrounding brain parenchyma, due to failure of the local antioxidant systems. ROS/RNS cause structural membrane damage, induce inflammation, and scavenge nitric oxide (NO) to yield peroxynitrite (ONOO(-)). This activates the inducible NO synthase, which further compounds ONOO(-) formation. ROS/RNS cause mitochondrial dysfunction by inhibiting the mitochondrial electron transport chain and uncoupling oxidative phosphorylation, which ultimately leads to neuronal bioenergetic failure. Furthermore, in certain 'at risk' areas of the brain, free radicals may induce neuronal apoptosis. In the present review, we define a role for ROS/RNS-mediated neuronal bioenergetic failure and apoptosis as a primary mechanism underlying sepsis-associated encephalopathy and, in sepsis survivors, permanent cognitive deficits.

Magnesium sulfate mitigates lung injury induced by bilateral lower limb ischemia-reperfusion in rats

BACKGROUND

Lower limb ischemia-reperfusion (I/R) elicits oxidative stress and causes inflammation in lung tissues that may lead to lung injury. Magnesium sulfate (MgSO(4)) possesses potent anti-oxidation and anti-inflammation capacity. We sought to elucidate whether MgSO(4) could mitigate I/R-induced lung injury. As MgSO(4) is an L-type calcium channel inhibitor, the role of the L-type calcium channels was elucidated.

MATERIALS AND METHODS

Adult male rats were allocated to receive I/R, I/R plus MgSO(4) (10, 50, or 100 mg/kg), or I/R plus MgSO(4) (100 mg/kg) plus the L-type calcium channels activator BAY-K8644 (20 μg/kg) (n = 12 in each group). Control groups were run simultaneously. I/R was induced by applying rubber band tourniquets high around each thigh for 3 h followed by reperfusion for 3 h. After euthanization, degrees of lung injury, oxidative stress, and inflammation were determined.

RESULTS

Arterial blood gas and histologic assays, including histopathology, leukocyte infiltration (polymorphonuclear leukocytes/alveoli ratio and myeloperoxidase activity), and lung water content, confirmed that I/R caused significant lung injury. Significant increases in inflammatory molecules (chemokine, cytokine, and prostaglandin E(2) concentrations) and lipid peroxidation (malondialdehyde concentration) confirmed that I/R caused significant inflammation and oxidative stress in rat lungs. MgSO(4), at the dosages of 50 and 100 mg/kg but not 10 mg/kg, attenuated the oxidative stress, inflammation, and lung injury induced by I/R. Moreover, BAY-K8644 reversed the protective effects of MgSO(4).

CONCLUSIONS

MgSO(4) mitigates lung injury induced by bilateral lower limb I/R in rats. The mechanisms may involve inhibiting the L-type calcium channels.

Magnesium sulfate ameliorates maternal and fetal inflammation in a rat model of maternal infection

OBJECTIVE

Magnesium sulfate is proposed to have neuroprotective effects in the offspring. We examined the effects of maternal magnesium sulfate administration on maternal and fetal inflammatory responses in a rat model of maternal infection.

STUDY DESIGN

Pregnant rats were injected with saline, Gram-negative bacterial endotoxin lipopolysaccharide or lipopolysaccharide with magnesium sulfate (pre- and/or after lipopolysaccharide) to mimic infection. Maternal blood, amniotic fluid, fetal blood, and fetal brains were collected 4 hours after lipopolysaccharide and assayed for tumor necrosis factor, interleukin-6, monocyte chemoattractant protein-1, and growth-related oncogene-KC. In addition, the effect of magnesium sulfate on cytokine production by an astrocytoma cell line was assessed.

RESULTS

Lipopolysaccharide administration induced tumor necrosis factor, interleukin-6, monocyte chemoattractant protein-1, and growth-related oncogene-KC expression in maternal and fetal compartments. Maternal magnesium sulfate treatment significantly attenuated lipopolysaccharide-induced multiple proinflammatory mediator levels in maternal and fetal compartments.

CONCLUSION

Antenatal magnesium sulfate administration significantly ameliorated maternal, fetal, and gestational tissue-associated inflammatory responses in an experimental model of maternal infection.

Assessment of permeability in barrier type of endothelium in brain using tracers: Evans blue, sodium fluorescein, and horseradish peroxidase

Blood-brain barrier (BBB) constituted primarily by the capillary endothelial cells functions to maintain a constant environment for the brain, by preventing or slowing down the passage of a variety of blood-borne substances, such as serum proteins, chemical compounds, ions, and hormones from the circulation into the brain parenchyma. Various diseases such as brain tumors, epilepsy, and sepsis disturb the BBB integrity leading to enhanced permeability of brain microvessels. In animal models, a variety of experimental insults targeted to the BBB integrity have been shown to increase BBB permeability causing enhanced passage of molecules into the brain paranchyma by transcellular and/or paracellular pathways. This alteration can be demonstrated by intravascular infusion of exogenous tracers and subsequent detection of extravasated molecules in the brain tissue. A number of exogenous BBB tracers are available, and they can be used for functional and structural analysis of BBB permeability. In this chapter, we aimed to highlight the basic knowledge on the use of three most commonly performed tracers, namely Evans blue dye, sodium fluorescein, and horseradish peroxidase. The experimental methodologies that we use in our laboratory for the detection of these tracers by macroscopy, spectrophotometry, spectrophotofluorometry, and electron microscopy are also discussed. While tracing studies at the morphological level are mainly aimed at the identification and characterization of the tracers both in the barrier related cells and brain parenchyma, spectrophotometric and spectrophotofluorometric assays enable quantification of BBB permeability. The results of our studies that we performed using the mentioned tracers indicate that barrier type of endothelial cells in brain play an important role in paracellular and/or transcytoplasmic trafficking of macromolecules across BBB under various experimental settings, which may provide new insights in both designing approaches for the management of diseases with BBB breakdown and developing novel trans-BBB drug delivery strategies.

Curcumin modulates leukocyte and platelet adhesion in murine sepsis

OBJECTIVE

Circulating cell-endothelial cell interaction in sepsis is a rate-determining factor in organ dysfunction, and interventions targeting this process have a potential therapeutic value. In this project, we examined whether curcumin, an active ingredient of turmeric and an anti-inflammatory agent, could disrupt interactions between circulating blood cells and endothelium and improve survival in a murine model of sepsis.

METHODS

Mice were subjected to cecal ligation and puncture (CLP) to induce sepsis vs. sham surgery. We studied leukocyte and platelet adhesion in cerebral microcirculation using intravital fluorescent video microscopy technique, blood-brain barrier (BBB) dysfunction using Evans Blue (EB) leakage method, P-selectin expression using dual radiolabeling technique, and survival in mice subjected to Sham, CLP, and CLP with curcumin pre-treatment (CLP + curcumin).

RESULTS

Curcumin significantly attenuated leukocyte and platelet adhesion in cerebral microcirculation, EB leakage in the brain tissue, and improved survival in mice with CLP. P-selectin expression in mice with CLP + curcumin was significantly attenuated compared with CLP in various microcirculatory beds, including brain. Reduction in platelet adhesion was predominantly via modulation of endothelium by curcumin.

CONCLUSION

Curcumin pre-treatment modulates leukocyte and platelet adhesion and BBB dysfunction in mice with CLP via P-selectin expression and improves survival in mice with CLP.

Sepsis-associated encephalopathy and its differential diagnosis

Sepsis-associated encephalopathy (SAE) is defined as a diffuse cerebral dysfunction resulting from the systemic inflammatory response to an infection without direct infestation of the CNS. Although the pathophysiology of SAE is as yet unknown, some mechanisms have been suggested that involve BBB disruption as a consequence of proinflammatory mediators’ effects on endothelial cells. This leads to an increased passage of neurotoxic and proinflammatory mediators into the brain parenchyma, as well as an impairment of the movements of oxygen and metabolites through the BBB. Both neurons and glial cells are affected, resulting in neural functioning and neurotransmission impairment. The clinical translation of this process is an alteration of consciousness and awareness. SAE is a frequent condition in septic patients. Despite being considered reversible, SAE appears to be associated with long-term cognitive impairment. Detection and diagnosis can be challenging; it requires daily neurological assessment with the assistance of clinical scores. Use of biomarkers and neurophysiological testing is discussed. The aim of this article is to provide practical tools for detection of SAE, as well as an updated overview of its pathophysiology and therapeutic perspectives.

Current and future treatment considerations in the management of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a type of hemorrhagic stroke that can cause significant morbidity and mortality. Although guidelines have been published to help direct the care of these patients, there is insufficient quality literature regarding the medical and pharmacological management of patients with aSAH. Treatment is divided into 3 categories: supportive therapy, prevention of complications, and treatment of complications. There are numerous pharmacological therapies that are targeted at prevention and treatment of the neurological and medical complications that may arise. Rebleeding, hydrocephalus, cerebral vasospasm, and seizures are the most common neurological complications while the most common medical complications include hyponatremia, pulmonary edema, cardiac arrhythmias, neurogenic stunned myocardium, fever, anemia, infection, hyperglycemia, and venous thromboembolism. Risk factors, clinical presentation, diagnosis, pathophysiology, as well as initial management, prevention, and treatment of complications will be the focus of this discussion.