Exacerbate Brain Damage Research Articles

Reduced expression of IA channels is associated with postischemic seizures in hyperglycemic rats

Poststroke seizures are considered to be the major cause of epilepsy in the elderly. The mechanisms of poststroke seizures remain unclear. A history of diabetes mellitus has been identified as an independent predictor of acute poststroke seizures in stroke patients. The present study sought to reveal the mechanisms for the development of postischemic seizures under hyperglycemic conditions. Transient forebrain ischemia was produced in adult Wistar rats by using the four-vessel occlusion method. At the normal blood glucose level, seizures occurred in ∼50% of rats after 25 min of ischemia. However, in rats with hyperglycemia, the incidence rate of postischemic seizures was significantly increased to 100%. The occurrence of postischemic seizures was not correlated with the severity of brain damage in hyperglycemic rats. Mannitol, an osmotic diuretic agent, could neither prevent postischemic seizures nor alleviate the exacerbated brain damage in the presence of hyperglycemia. K(+) channels play a critical role in controlling neuronal excitability. The expression of A-type K(+) channel subunit Kv4.2 in the hippocampus and the cortex was significantly reduced in hyperglycemic rats with seizures compared with those without seizures. These results suggest that the reduction of Kv4.2 expression could contribute to the development of postischemic seizures in hyperglycemia.

Increased on oxidative brain injury in the diabetic rats following sepsis.

Diabetes has been the subject of recent research by increase susceptibility to infections, thus the aim of this study was to evaluate in animal model of diabetes induced by alloxan (ALX) and subjected to sepsis the parameters of oxidative stress on the brain. Diabetes was induced in Wistar rats by ALX (150 mg/kg), and 15 days after, sepsis was induced by cecal ligation and puncture (CLP). The myeloperoxidase activity (MPO), nitrite/nitrate, oxidative damage parameters, and the activity of superoxide dismutase (SOD) and catalase (CAT) were measured in the cerebellum, hippocampus, striatum, prefrontal, and cortex in 6, 12, and 24 h after CLP. The results showed the potentiation of diabetes with sepsis. We verified these potentiation on MPO levels in the cerebellum, hippocampus, and prefrontal and an increase of the nitrite/nitrate concentration in the hippocampus, striatum, prefrontal, and cortex in 24 h after sepsis surgery. To oxidative damage, we verified in 6 h an increase on lipid and protein damage parameters in the striatum and hippocampus in 24 h. When we associate sepsis and diabetes, the SOD and CAT activity not were altered. Thus, diabetes associated with sepsis exacerbates brain damage resulting from inflammation and oxidative stress in brain.

Neuro‐glio‐vascular dysfunction and epigenetic remodeling in diabetic stroke (1126.19)

Clinical studies demonstrate that stroke in diabetes leads to exacerbated brain damage and functional decline but the nature and mechanisms are still undefined. Therefore, we hypothesize that stroke in diabetes severely disturbed neuro‐glio‐vascular unit and cognitive functions instigated by epigenetic remodeling. To test this hypothesis, we employed 8‐10 week‐old male C57BL/6J (WT) sham, WT+ ischemia reperfusion (I/R), Akita (Ins2+/‐, diabetic) sham, and Akita+I/R, mice groups. Ischemia was performed for 60 min and reperfusion for 24 h. Infarct area and edema were measured with 2,3,5‐triphenyltetrazolium chloride and Evans blue extravasation, respectively. We found that infarct area, edema, and brain functions (memory, hearing) are severely affected in Akita I/R as compared to I/R group. DNMTs and HDACs activity/expressions were highly altered in Akita I/R, as compared to I/R and sham operated groups, signifies epigenetic alterations. Molecular assessments exemplified Akita I/R severity, as compared to IR group, in terms of increase in white matter damage (amyloid beta), matrix metalloproteinase (MMP‐9), glutamatergic response (NMDA), and permeability of blood vessels. On contrary, Akita I/R exhibited decrease in neural differentiation (netrin‐1, nestin) and tight junctions (ZO‐1, claudin‐5) protein/transcript expressions as compared to I/R and sham operated groups. Immunohistochemistry studies determined deep alterations of vascular connections (Cx45, CD31, GFAP) and ion channels (Na+‐K+, Ca++) in Akita I/R as compared to I/R group. These results suggest stroke severity in diabetic brain due to intense damage in neuro‐glio‐vascular unit with epigenetic remodeling and stipulate treatments much needed to be explored.Grant Funding Source: HL107640

Antenatal dexamethasone after asphyxia increases neural injury in preterm fetal sheep.

Background and PurposeMaternal glucocorticoid treatment for threatened premature delivery dramatically improves neonatal survival and short-term morbidity; however, its effects on neurodevelopmental outcome are variable. We investigated the effect of maternal glucocorticoid exposure after acute asphyxia on injury in the preterm brain.MethodsChronically instrumented singleton fetal sheep at 0.7 of gestation received asphyxia induced by complete umbilical cord occlusion for 25 minutes. 15 minutes after release of occlusion, ewes received a 3 ml i.m. injection of either dexamethasone (12 mg, n = 10) or saline (n = 10). Sheep were killed after 7 days recovery; survival of neurons in the hippocampus and basal ganglia, and oligodendrocytes in periventricular white matter were assessed using an unbiased stereological approach.ResultsMaternal dexamethasone after asphyxia was associated with more severe loss of neurons in the hippocampus (CA3 regions, 290±76 vs 484±98 neurons/mm2, mean±SEM, P<0.05) and basal ganglia (putamen, 538±112 vs 814±34 neurons/mm2, P<0.05) compared to asphyxia-saline, and with greater loss of both total (913±77 vs 1201±75/mm2, P<0.05) and immature/mature myelinating oligodendrocytes in periventricular white matter (66±8 vs 114±12/mm2, P<0.05, vs sham controls 165±10/mm2, P<0.001). This was associated with transient hyperglycemia (peak 3.5±0.2 vs. 1.4±0.2 mmol/L at 6 h, P<0.05) and reduced suppression of EEG power in the first 24 h after occlusion (maximum −1.5±1.2 dB vs. −5.0±1.4 dB in saline controls, P<0.01), but later onset and fewer overt seizures.ConclusionsIn preterm fetal sheep, exposure to maternal dexamethasone during recovery from asphyxia exacerbated brain damage.

PRO: Regulatory T Cells Are Protective in Ischemic Stroke

Immune disturbances play manifold roles in the pathogenesis of ischemic stroke. Regulatory mechanisms that continuously fine-tune the immune system are, therefore, essential for protection and recovery from stroke. Regulatory T cells (Tregs) is suggested to exert neuroprotection by Liesz et al1 on the basis of their findings that Tregs depletion with CD25 antibody exacerbates brain damage and worsens functional deficits 7 days after transient ischemic stroke. The endogenous Treg-afforded protection is late in onset, as Treg depletion failed to influence brain damage ≤4 days post ischemia.1–3 This late action is consistent with delayed Treg infiltration into the brain until 3 to 5 days after middle cerebral artery occlusion.1 Interestingly, anti-inflammatory effects of Tregs were observed before their appearance in the brain, suggesting early peripheral protective mechanisms of Tregs.1 Such anti-inflammatory effects, however, are not potent enough to reduce early brain damage, probably because of insufficient Treg numbers in the circulation. In support, clinical studies report that the number of circulating Tregs decreases transiently, but dramatically in the first 2 days after stroke.4 Therefore, …

Myeloperoxidase-Derived Oxidants Induce Blood-Brain Barrier Dysfunction In Vitro and In Vivo

Peripheral leukocytes can exacerbate brain damage by release of cytotoxic mediators that disrupt blood-brain barrier (BBB) function. One of the oxidants released by activated leukocytes is hypochlorous acid (HOCl) formed via the myeloperoxidase (MPO)-H2O2-Cl− system. In the present study we examined the role of leukocyte activation, leukocyte-derived MPO and MPO-generated oxidants on BBB function in vitro and in vivo. In a mouse model of lipopolysaccharide (LPS)-induced systemic inflammation, neutrophils that had become adherent released MPO into the cerebrovasculature. In vivo, LPS-induced BBB dysfunction was significantly lower in MPO-deficient mice as compared to wild-type littermates. Both, fMLP-activated leukocytes and the MPO-H2O2-Cl− system inflicted barrier dysfunction of primary brain microvascular endothelial cells (BMVEC) that was partially rescued with the MPO inhibitor 4-aminobenzoic acid hydrazide. BMVEC treatment with the MPO-H2O2-Cl− system or activated neutrophils resulted in the formation of plasmalogen-derived chlorinated fatty aldehydes. 2-chlorohexadecanal (2-ClHDA) severely compromised BMVEC barrier function and induced morphological alterations in tight and adherens junctions. In situ perfusion of rat brain with 2-ClHDA increased BBB permeability in vivo. 2-ClHDA potently activated the MAPK cascade at physiological concentrations. An ERK1/2 and JNK antagonist (PD098059 and SP600125, respectively) protected against 2-ClHDA-induced barrier dysfunction in vitro. The current data provide evidence that interference with the MPO pathway could protect against BBB dysfunction under (neuro)inflammatory conditions.

Adoptive regulatory T‐cell therapy protects against cerebral ischemia

Recent evidence suggests that functional deficiency in regulatory T cells (Tregs), an innate immunomodulator, exacerbates brain damage after cerebral ischemia. We therefore evaluated the effect of Treg transfer in rodent models of ischemic stroke and further investigated the mechanism underlying Treg-afforded neuroprotection. We examined the therapeutic potential of Tregs and the mechanisms of neuroprotection in vivo in 2 rodent models of ischemic stroke and in vitro in Treg-neutrophil cocultures using a combined approach including cell-specific depletion, gene knockout mice, and bone marrow chimeras. Systemic administration of purified Tregs at 2, 6, or even 24 hours after middle cerebral artery occlusion resulted in a marked reduction of brain infarct and prolonged improvement of neurological functions lasting out to 4 weeks. Treg-afforded neuroprotection was accompanied by attenuated blood-brain barrier (BBB) disruption during early stages of ischemia, decreased cerebral inflammation, and reduced infiltration of peripheral inflammatory cells into the lesioned brain. Surprisingly, Tregs exerted early neuroprotection without penetrating into the brain parenchyma or inhibiting the activation of residential microglia. Rather, both in vivo and in vitro studies demonstrated that Tregs suppressed peripheral neutrophil-derived matrix metallopeptidase-9 production, thus preventing proteolytic damage of the BBB. In addition to its potent central neuroprotection, Treg treatment was shown to ameliorate poststroke lymphopenia, suggesting a beneficial effect on immune status. Our study suggests that Treg adoptive therapy is a novel and potent cell-based therapy targeting poststroke inflammatory dysregulation and neurovascular disruption.

Abstract TMP34: Prostaglandin PGF2a Receptors as a Putative Therapeutic Target in Stroke and Traumatic Brain Injury

Background: Stroke and traumatic brain injury (TBI) are ones of the leading causes of death and disability in the USA. Secondary brain injury following TBI shares common features with neuropathology of stroke including oxidative stress and neuroinflammation. Although potentially treatable secondary injuries play a key role in the neurological outcomes currently there is no effective treatment and discovery of new therapeutic targets remains critical. Primary injury to the brain promotes upregulation of prostaglandins, notably the proinflammatory PGF2a, and overactivation of its FP GPCR which could exacerbate brain damage. Thus, our study is focused on the investigation of the FP receptor as a target for novel neuroprotective drugs in preclinical animal models of stroke and TBI. Methods: We used FP receptor knockout male C57BL/6 mice and post-treatment with the selective FP antagonist AL-8810 (1 and 10mg/kg, IP) in permanent middle cerebral artery occlusion (pMCAO) and controlled cortical impact (CCI) models. Neurological impairments assessed at 24 and 48h after injury using tape removal reflex and neurological deficit score, and brain pathology was assessed at 48h using triphenyltetrazolium chloride or cresyl violet. Results: Genetic deletion of the FP receptor or its blockade with AL-8810 at both doses significantly reduced cortical infarct volume and tape removal reflex following pMCAO. In vehicle treated animals, CCI caused cortical lesion with relative volume of 20.5±1.0% and significant hippocampal swelling (146.5±7.4% of contralateral) as compared with sham (P&lt;0.05, n=4). AL-8810 had no significant effect on cortical lesion suggesting irreversible effect of primary CCI injury. However, AL-8810 at both doses reduced CCI-induced hippocampal swelling to the levels not significantly different from the sham. In CCI model, post-treatment with AL-8810 at dose 10mg/kg significantly improved neurological deficit score at 24 and 48h after CCI (P&lt;0.001 and P&lt;0.01, n=9-10); whereas the effect of 1mg/kg dose was not significant. Conclusion: This study provided, for the first time, clarification on the respective role of calcium-modulating PGF2a FP receptor as a potential target for disease-modifying CNS drugs for treatment of stroke and TBI.

Protection against Recurrent Stroke with Resveratrol: Endothelial Protection

Despite increased risk of a recurrent stroke following a minor stroke, information is minimal regarding the interaction between injurious mild cerebral ischemic episodes and the possible treatments which might be effective. The aim of the current study was to investigate recurrent ischemic stroke and whether resveratrol, a nutritive polyphenol with promising cardio- and neuro- protective properties, could ameliorate the associated brain damage. Experiments in adult rats demonstrated that a mild ischemic stroke followed by a second mild cerebral ischemia exacerbated brain damage, and, daily oral resveratrol treatment after the first ischemic insult reduced ischemic cell death with the recurrent insult (P<0.002). Further investigation demonstrated reduction of both inflammatory changes and markers of oxidative stress in resveratrol treated animals. The protection observed with resveratrol treatment could not be explained by systemic effects of resveratrol treatment including effects either on blood pressure or body temperature measured telemetrically. Investigation of resveratrol effects on the blood-brain barrier in vivo demonstrated that resveratrol treatment reduced blood-brain barrier disruption and edema following recurrent stroke without affecting regional cerebral blood flow. Investigation of the mechanism in primary cell culture studies demonstrated that resveratrol treatment significantly protected endothelial cells against an in vitro ‘ischemia’ resulting in improved viability against oxygen and glucose deprivation (39.6±6.6% and 81.3±9.5% in vehicle and resveratrol treated cells, respectively). An inhibition of nitric oxide synthesis did not prevent the improved cell viability following oxygen glucose deprivation but SIRT-1 inhibition with sirtinol partially blocked the protection (P<0.001) suggesting endothelial protection is to some extent SIRT-1 dependent. Collectively, the results support that oral resveratrol treatment provides a low risk strategy to protect the brain from enhanced damage produced by recurrent stroke which is mediated in part by a protective effect of resveratrol on the endothelium of the cerebrovasculature.

Targeting reactive nitrogen species: a promising therapeutic strategy for cerebral ischemia-reperfusion injury

Ischemic stroke accounts for nearly 80% of stroke cases. Recanalization with thrombolysis is a currently crucial therapeutic strategy for re-building blood supply, but the thrombolytic therapy often companies with cerebral ischemia-reperfusion injury, which are mediated by free radicals. As an important component of free radicals, reactive nitrogen species (RNS), including nitric oxide (NO) and peroxynitrite (ONOO(-)), play important roles in the process of cerebral ischemia-reperfusion injury. Ischemia-reperfusion results in the production of nitric oxide (NO) and peroxynitrite (ONOO(-)) in ischemic brain, which trigger numerous molecular cascades and lead to disruption of the blood brain barrier and exacerbate brain damage. There are few therapeutic strategies available for saving ischemic brains and preventing the subsequent brain damage. Recent evidence suggests that RNS could be a therapeutic target for the treatment of cerebral ischemia-reperfusion injury. Herein, we reviewed the recent progress regarding the roles of RNS in the process of cerebral ischemic-reperfusion injury and discussed the potentials of drug development that target NO and ONOO(-) to treat ischemic stroke. We conclude that modulation for RNS level could be an important therapeutic strategy for preventing cerebral ischemia-reperfusion injury.

Effects of vascular endothelial growth factor in ischemic stroke

Vascular endothelial growth factor (VEGF) is a pleiotropic growth factor that is crucially involved in neurovascular remodeling in the ischemic brain. VEGF promotes angiogenesis, protects ischemic neurons from injury, has potent anti-inflammatory actions, and promotes brain plasticity, in addition to enhancing the recruitment and proliferation of neural precursor cells. These broad actions make VEGF interesting as a model molecule that allows understanding endogenous responses of the brain to injuries. However, several studies indicate that the route and timing of VEGF administration are crucial for the effects of VEGF on ischemic brain tissue. Hence, systemic VEGF delivery in the very acute stroke phase may exacerbate brain damage because of the promotion of blood-brain barrier breakdown that inevitably accompanies vascular growth. Future studies aimed at the promotion of neurovascular remodeling in ischemic stroke should carefully take into consideration pleiotropic actions of angiogenic growth factors beyond vascular growth.

Hyperglycemia Alters Mitochondrial Fission and Fusion Proteins in Mice Subjected to Cerebral Ischemia and Reperfusion

Preischemic hyperglycemia exacerbates brain damage caused by cerebral ischemia. In the present experiment, we studied the effects of preischemic hyperglycemia on protein markers that are related to mitochondrial fission and fusion, mitochondrial biogenesis, and autophagy in mice subjected to 30-min transient focal ischemia. The fission proteins dynamin-related protein 1 (Drp1) and fission 1 (Fis1), fusion proteins optic atrophy 1 (Opa1) and mitofusin 2 (Mfn2), mitochondrial biogenesis regulators nuclear respiratory factor 1 (NRF1) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), and autophagy marker beclin 1 and microtubule-associated protein light chain 3 (LC3) were analyzed in control, 30 min middle cerebral artery occlusion (MCAO) plus 6-, 24-, and 72 h of reperfusion in normo- and hyperglycemic conditions. Cerebral ischemia increased the levels of Drp1 and decreased Fis1 after reperfusion. Preischemic hyperglycemia further augmented the increase of Drp1 and induced elevation in Fis1. Ischemia inhibited the levels of Opa1 and Mfn2 and hyperglycemia further decreased the level of Opa1. Further, NRF1 increased after reperfusion in both normo- and hyperglycemic animals. However, such increase was caused by reperfusion rather than glucose level. Finally, ischemia increased beclin 1 level at 6 and 24 h of reperfusion and hyperglycemia further increased the beclin 1 level and caused LC3-II increase as well. Hyperglycemia enhances the ischemia-induced mitochondrial dynamic imbalance towards fission that may favor mitochondrial fragmentation and subsequent damage. Hyperglycemia elevated autophagy markers may represent an adapting reaction to the severe damage incurred in hyperglycemic animals or a third pathway of cell death.

Immediate, but not delayed, microsurgical skull reconstruction exacerbates brain damage in experimental traumatic brain injury model.

Moderate to severe traumatic brain injury (TBI) often results in malformations to the skull. Aesthetic surgical maneuvers may offer normalized skull structure, but inconsistent surgical closure of the skull area accompanies TBI. We examined whether wound closure by replacement of skull flap and bone wax would allow aesthetic reconstruction of the TBI-induced skull damage without causing any detrimental effects to the cortical tissue. Adult male Sprague-Dawley rats were subjected to TBI using the controlled cortical impact (CCI) injury model. Immediately after the TBI surgery, animals were randomly assigned to skull flap replacement with or without bone wax or no bone reconstruction, then were euthanized at five days post-TBI for pathological analyses. The skull reconstruction provided normalized gross bone architecture, but 2,3,5-triphenyltetrazolium chloride and hematoxylin and eosin staining results revealed larger cortical damage in these animals compared to those that underwent no surgical maneuver at all. Brain swelling accompanied TBI, especially the severe model, that could have relieved the intracranial pressure in those animals with no skull reconstruction. In contrast, the immediate skull reconstruction produced an upregulation of the edema marker aquaporin-4 staining, which likely prevented the therapeutic benefits of brain swelling and resulted in larger cortical infarcts. Interestingly, TBI animals introduced to a delay in skull reconstruction (i.e., 2 days post-TBI) showed significantly reduced edema and infarcts compared to those exposed to immediate skull reconstruction. That immediate, but not delayed, skull reconstruction may exacerbate TBI-induced cortical tissue damage warrants a careful consideration of aesthetic repair of the skull in TBI.

Attenuation of Astrocyte Activation by TAT-Mediated Delivery of a Peptide JNK Inhibitor

Astrocyte activation contributes to the brain's response to disease and injury. Activated astrocytes generate harmful radicals that exacerbate brain damage including nitric oxide, peroxides and superoxides. Furthermore, reactive astrocytes hinder regeneration of damaged neural circuits by secreting neuro-developmental inhibitors and glycosaminoglycans (GAGs), which physically block growth cone extension. Therefore, targeted therapeutic strategies to limit astrocyte activation may enhance recovery from many neurodegenerative states. Previously, we demonstrated that the HIV-1 TAT cell-penetrating peptide, a short non-toxic peptide from the full-length TAT protein, delivered a protein cargo to astrocytes in a process dependent on cell-surface GAG. Since activated astrocytes produce GAG, in this study we tested whether TAT could transduce activated astrocytes, deliver a biologically active cargo, and produce a physiological effect. Astrocyte activation was induced by IL-1β, lipopolysaccharide (LPS), or mechanical stretch injury, and quantified by increased GAG and nitrite content. TAT-mediated delivery of a mock therapeutic protein, GFP, increased significantly after activation. Nitrite production, GAG expression, and GFP-TAT transduction were significantly attenuated by inhibitors of JNK, p38, or ERK. TAT fused to a peptide JNK inhibitor delivered the peptide inhibitor to activated astrocytes and significantly reduced activation. Our study is the first to report significant and direct modulation of astrocyte activation with a peptide JNK inhibitor. Our promising in vitro results warrant in vivo follow-up, as TAT-mediated protein delivery may have broad therapeutic potential for preventing astrocyte activation with the possibility of limiting off-target, negative side effects.

Spatial and temporal patterns of oxidative stress in the brain of gerbils submitted to different duration of global cerebral ischemia

The present study was undertaken to examine spatial and temporal patterns of oxidative stress rate in the brain of Mongolian gerbils submitted to different duration of global ischemia/reperfusion. The common carotid arteries of gerbils were occluded for 5, 10, or 15 min. We followed the temporal ischemia-induced oxidative stress rate, the most important factor that exacerbates brain damage by reperfusion, starting from 24 h up to 28 days after reperfusion. The spatial ischemia-induced oxidative stress distribution was measured parallely in different brain regions: forebrain cortex, striatum, hippocampus and cerebellum. Post-ischemic effects were followed in vivo by monitoring the neurological status of whole animals and at the intracellular level by standard biochemical assays in different brain regions. We measured superoxide production, superoxide dismutase activity, nitric oxide production, index of lipid peroxidation, and reduced glutathione. Our results revealed a pattern of dynamic changes in each oxidative stress parameter that corresponded with ischemia duration in all tested brain structures. The highest levels were obtained in the first 24 h after the insult. After that, they slowly returned to nearly control values 28 days after reperfusion (with the exception of SOD activity that returned to control values at fourth day after reperfusion). The most sensitive oxidative stress parameter was index of lipid peroxidation. Our study confirmed spatial distribution of ischemia-induced oxidative stress. Tested brain structures showed different sensitivity to each oxidative stress parameter, although their basal levels were similar. These new findings could be valuable for creation and strategy of post-ischemic therapy.

Malnutrition in Patients with Acute Stroke

Stroke is a devastating event that carries a potential for long-term disability. Malnutrition is frequently observed in patients with stroke, and dysphagia contributes to malnutrition risk. During both the acute phase of stroke and rehabilitation, specific nutritional interventions in the context of a multidisciplinary team effort can enhance the recovery of neurocognitive function. Early identification and management of malnutrition with dietary modifications or specific therapeutic strategies to ensure adequate nutritional intake should receive more attention, since poor nutritional status appears to exacerbate brain damage and to contribute to adverse outcome. The main purpose of nutritional intervention should be the prevention or treatment of complications resulting from energy-protein deficit. This paper reviews the evaluation and management of malnutrition and the use of specialized nutrition support in patients with stroke. Emphasis is given to enteral tube and oral feeding and to strategies to wean from tube feeding.

High Blood Glucose Does Not Adversely Affect Outcome in Moderately Brain-Injured Rodents

In a number of clinical studies researchers have reported that acute hyperglycemia is associated with increased mortality and worsened neurological outcome in patients with traumatic brain injury (TBI). In contrast, it has been demonstrated that intensive insulin therapy to lower blood glucose can lead to an increased frequency of hypoglycemic episodes and poor outcome. Consistent with this, experimental and clinical studies have shown that TBI causes a "metabolic crisis" in the injured brain, suggesting that a reduction in glucose availability may exacerbate brain damage. We therefore examined the consequences of hyperglycemia on cognitive and pathological measures. Using a rodent model of TBI, we find that when acute hyperglycemia is induced in animals prior to injury, there is little to no change in motor and cognitive performance, contusion volume, or cerebral edema. To examine the consequences of persistent hyperglycemia (as seen in diabetic patients), animals were treated with streptozotocin (STZ) to induce type 1 diabetes. We find that the presence of persistent STZ-induced hyperglycemia results in a reduction of brain edema. Insulin therapy to reduce blood glucose reverses this beneficial effect of hyperglycemia. Taken together, our results indicate that an acute increase in blood glucose levels may not be harmful, and that intervention with insulin therapy to lower blood glucose levels in TBI patients may increase secondary brain damage.

Chronic Systemic Infection Exacerbates Ischemic Brain Damage via a CCL5 (Regulated on Activation, Normal T-Cell Expressed and Secreted)-Mediated Proinflammatory Response in Mice

Infection and systemic inflammation are risk factors for cerebrovascular diseases and poststroke infections impair outcome in stroke patients, although the mechanisms of their contribution are mostly unknown. No preclinical studies have identified how chronic infection affects ischemic brain damage and which key inflammatory mediators are involved. We used a well established model of gut infection (Trichuris muris) to study how chronic infection contributes to brain injury. We show that, in mice, infection that leads to a chronic Th1-polarized immune response dramatically (60%) exacerbates brain damage caused by experimental stroke. Chronic Th1-type infection resulted in systemic upregulation of proinflammatory mediators and profoundly altered stroke-induced early (40 min to 4 h) and late (48 h) inflammation in the brain and peripheral tissues. Using the same infection, we show that a Th1-, but not Th2-polarized response augments brain injury by increasing the Th1 chemokine CCL5 [regulated on activation, normal T-cell expressed and secreted (RANTES)] systemically. This infection-associated response paralleled altered regulatory T-cell response, accelerated platelet aggregation in brain capillaries, and increased microvascular injury and matrix metalloproteinase activation after stroke. Antibody neutralization of RANTES reversed the effect of chronic infection on brain damage, microvascular MMP-9 activation, and cellular inflammatory response. Our results suggest that chronic infection exacerbates ischemic brain damage via a RANTES-mediated systemic inflammatory response, which leads to delayed resolution of inflammation and augmented microvascular injury in the brain.

MK-801 effect on regional cerebral oxidative stress rate induced by different duration of global ischemia in gerbils

We investigated MK-801 effect on ischemia-induced oxidative stress-the most important factor that exacerbates brain damage by reperfusion. The common carotid arteries of gerbils were occluded for 5, 10, or 15 min. Immediately after the occlusion, MK-801 (3 mg/kg i.p.) or saline were given in normothermic conditions. The MK-801 effects were followed in vivo by monitoring the neurological status of animals and at the intracellular level by standard biochemical assays. We investigated nitric oxide levels, superoxide production, superoxide dismutase activity, index of lipid peroxidation (ILP), and reduced glutathione content in hippocampus, striatum, forebrain cortex, and cerebellum. The measurements took place at different times (1, 2, 4, 7, 14, and 28 days) after reperfusion. Increased duration of cerebral ischemia resulted in a progressive induction of oxidative stress. Our results revealed pattern of dynamic changes in each oxidative stress parameter level which corresponded with ischemia duration in all tested brain structures. Most sensitive oxidative stress parameters were ILP and superoxide production. Our study confirmed spatial distribution of ischemia-induced oxidative stress. Tested brain structures showed different sensitivity to each oxidative stress parameter. As judged by biochemical and neurological data, applied MK-801 showed neuroprotective efficiency by reduction of ischemia-induced oxidative stress in brain.

P-154 Down-Regulation of Cellular FAK Protein Results in Enhanced Caspase-3 Activation and Exacerbation of Brain Damage in Hypertensive Rats

P-154 Down-Regulation of Cellular FAK Protein Results in Enhanced Caspase-3 Activation and Exacerbation of Brain Damage in Hypertensive Rats