Formation Of Vasogenic Brain Edema Research Articles

Characterization of Vasogenic and Cytotoxic Brain Edema Formation After Experimental Traumatic Brain Injury by Free Water Diffusion Magnetic Resonance Imaging.

Brain edema formation is a key factor for secondary tissue damage after traumatic brain injury (TBI), however, the type of brain edema and the temporal profile of edema formation are still unclear. We performed free water imaging, a bi-tensor model based diffusion MRI analysis, to characterize vasogenic brain edema (VBE) and cytotoxic edema (CBE) formation up to 7 days after experimental TBI. Male C57/Bl6 mice were subjected to controlled cortical impact (CCI) or sham surgery and investigated by MRI 4h, 1, 2, 3, 5, and 7 days thereafter (n = 8/group). We determined mean diffusivity (MD) and free water (FW) in contusion, pericontusional area, ipsi- and contralateral brain tissue. Free (i.e., non-restricted) water was interpreted as VBE, restricted water as CBE. To verify the results, VBE formation was investigated by in-vivo 2-Photon Microscopy (2-PM) 48h after surgery. We found that MD and FW values decreased for 48h within the contusion, indicating the occurrence of CBE. In pericontusional tissue, MD and FW indices were increased at all time points, suggesting the formation of VBE. This was consistent with our results obtained by 2-PM. Taken together, CBE formation occurs for 48h after trauma and is restricted to the contusion, while VBE forms in pericontusional tissue up to 7 days after TBI. Our results indicate that free water magnetic resonance imaging may represent a promising tool to investigate vasogenic and cytotoxic brain edema in the laboratory and in patients.

Longitudinal Characterization of Blood-Brain Barrier Permeability after Experimental Traumatic Brain Injury by In Vivo 2-Photon Microscopy.

Vasogenic brain edema (VBE) formation remains an important factor determining the fate of patients with traumatic brain injury (TBI). The spatial and temporal development of VBE, however, remains poorly understood because of the lack of sufficiently sensitive measurement techniques. To close this knowledge gap, we directly visualized the full time course of vascular leakage after TBI by in vivo 2-photon microscopy (2-PM). Male C57BL/6 mice (n = 6/group, 6-8 weeks old) were assigned randomly to sham operation or brain trauma by controlled cortical impact. A cranial window was prepared, and tetramethylrhodamine-dextran (TMRM, MW 40,000 Da) was injected intravenously to visualize blood plasma 4 h, 24 h, 48 h, 72 h, or seven days after surgery or trauma. Three regions with increasing distance to the primary contusion were investigated up to a depth of 300 μm by 2-PM. No TMRM extravasation was detected in sham-operated mice, while already 4 h after TBI vascular leakage was significantly increased (p < 0.05 vs. sham) and reached its maximum at 48 h after injury. Vascular leakage was most pronounced in the vicinity of the contusion. The rate of extravasation showed a biphasic pattern, peaking 4 h and 48-72 h after trauma. Taken together, longitudinal quantification of vascular leakage after TBI in vivo demonstrates that VBE formation after TBI develops in a biphasic manner suggestive of acute and delayed mechanisms. Further studies using the currently developed dynamic in vivo imaging modalities are needed to investigate these mechanisms and potential therapeutic strategies in more detail.

Glucocorticoid In Cytotoxicity Followed by Delayed Edema

Background: Cytotoxicity is the toxicity to cell. Any type of brain oedema producing raised intracranial pressure (ICP) which may be a fatal pathological state. Corticosteroid is contraindicated in cytotoxic brain oedema but in vasogenic oedema, it is beneficial. Cytotoxic oedema in its consequences induces vasogenic oedema where the corticosteroid may helpful.&#x0D; Objectives: To determine the effects of corticosteroid on tertiary vasogenic brain oedema from cytotoxic edema.&#x0D; Methods: Total of 328 patients was diagnosed as brain oedema and they had been first time reported &amp; all were admitted in Combined Military Hospital (CMH) Dhaka, between Jan 2017 to Jun 2019. Out of 328 patients, brain oedema due to spontaneous ICHs was 219 (66.77%) and traumatic ICHs were 109(33.33%). Diagnosis was based upon history, clinical examination and non-contrast Computed Tomography (CT) scan of brain.&#x0D; Results: Total 328 admitted patients in CMH Dhaka from Jan 2017-Jun 2019 were included in our study who full-fill the criteria. Males were 231 (70.43%); females were 97(29.57%) and were aged between 1 to 95 year. Intracranial haemorrhage rate among age group less than 55 years old being 76 (34.70%) and 55 years or above 143 (65.30%) of total 219 patients. Traumatic ICHs were 109 and 1 to 44 years age is most vulnerable, 69(63.30%) and 45 years and above 40 (36.70%) patients. Corticosteroid was used after vasogenic brain oedema formation following cytotoxic oedema which was diagnosed mainly radiologically. Cytotoxic oedema induced by 24 hours and vasogenic oedema in two to four days of brain insult. Vasogenic oedema developed in 24 -48 hours, 65 (19.82%) patients and 117 (35.67 %) by 48-72 hours and above 72 hours rest 146 (44.51%) patients after brain insult. After vasogenic oedema formation, out of 164 patients that is 50% patients were treated with corticosteroid and GOS was assessed- GOS 4,5 -103(62.80%), GOS 3-34 (20.73%), GOS 2- 23(14.02%) and GOS 1-4(2.44%) whereas without corticosteroid treatment of rest vasogenic oedema 164 (50%) , GOS was- GOS 4,5 -85(51.83%), GOS 3-43 (26.22%), GOS 2- 27(16.46%) and GOS 1-9(5.49%) at 30 days of incidence. There is more than two times mortality without corticosteroid therapy than with steroid therapy.&#x0D; Conclusion: Cytotoxic brain oedema is contraindicated for steroid but we observed that corticosteroid gives better GOS in vasogenic oedema which develops after cytotoxic brain oedema. Outcome in cytotoxic oedema followed by vasogenic oedema is beneficial for corticosteroid.&#x0D; Bang. J Neurosurgery 2020; 10(1): 45-51

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 (300mg/kg loading dose, followed by an additional 100mg/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.

5-Hydroxytryptophan: A precursor of serotonin influences regional blood-brain barrier breakdown, cerebral blood flow, brain edema formation, and neuropathology.

5-Hydroxytryptophan (5-HTP), a precursor of serotonin, is therapeutically used for several psychiatric disorders such as anxiety and depression in the clinic. However, severe side effects, including abnormal mental functions, behavioral disturbances and intolerance are associated with this treatment. 5-HTP-induced elevation of plasma and brain serotonin levels may affect blood-brain barrier (BBB) breakdown, edema formation and regional cerebral blood flow (CBF) disturbances. Breakdown of BBB to serum proteins leads to vasogenic brain edema formation and cellular injuries. However, 5-HTP-neurotoxicity is still not well known. In this investigations 5-HTP induced elevation of endogenous plasma and brain serotonin levels and its effect on BBB breakdown, edema formation neuronal injuries was examined in a rat model. Furthermore, potential role of oxidative stress and nitric oxide (NO) was evaluated. In addition, several neurochemical agents such as p-CPA (5-HT synthesis inhibitor) indomethacin (prostaglandin synthase inhibitor), diazepam (ant stress drug), cyproheptadine, ketanserin (5-HT2 receptor antagonists) and vinblastine (inhibitor of microtubule function) were examined on 5-HT neurotoxicity. Our observations suggest that 4h after 5-HTP administrations, the endogenous serotonin levels increased by fourfold (150mg/kg) in the plasma and brain associated with profound hyperthermia (+3.86±0.24°C, oxidative stress and NO upregulation. Breakdown of the BBB to Evans blue albumin (EBA) in 8 brain regions and to [131]Iodine in 14 brain regions was observed. The CBF exhibited marked reduction in all the brain regions examined. Brain edema and cellular injuries are present in the areas associated with BBB disruption. Drug treatments reduced the BBB breakdown, edema formation NO production and brain pathology. These observations are the first to point out that 5-HTP-neurotoxicity caused by BBB breakdown, edema formation and NO production is instrumental in causing adverse mental and behavioral abnormalities, not reported earlier.

Neuroprotective effects of a potent bradykinin B2 receptor antagonist HOE-140 on microvascular permeability, blood flow disturbances, edema formation, cell injury and nitric oxide synthase upregulation following trauma to the spinal cord.

Bradykinin is a mediator of vasogenic brain edema formation. Recent reports suggest that bradykinin interacts with nitric oxide synthase (NOS) system in the central nervous system (CNS). However, role of bradykinin in spinal cord injury (SCI) induced alterations in the blood-spinal cord barrier (BSCB), spinal cord blood flow (SCBF), edema formation and cell changes are still not well known. Our previous reports showed that SCI induces marked upregulation of neuronal NOS (nNOS) in the cord associated with BSCB disruption, edema formation and cell injury. Thus, a possibility exists that bradykinin participates in SCI induced nNOS upregulation and cord pathology. To explore this idea a potent bradykinin B2 receptor antagonist HOE-140 was used in our rat model of SCI and cord pathology. SCI was inflicted in Equithesin anesthetized rats by making a longitudinal incision (2mm deep and 5mm long) into the right dorsal horn of the T10-11 segment. The animals were allowed to survive 5h after injury. A focal SCI significantly disrupted BSCB to Evans blue and [131]I-sodium in the traumatized and adjacent segments. Interestingly, far remote spinal cord segments C4 and T5 segments also affected within 5h. These spinal cord segments also exhibited pronounced reductions in the SCBF (mean-30%), increased edematous swelling and profound neuronal damages. Upregulation of nNOS expression is seen in both the dorsal and ventral horns of the spinal cord exhibiting cord pathology. At the ultrastructural level, exudation of lanthanum is seen within the endothelial cell cytoplasm and occasionally in the basal lamina. Pretreatment with low doses of HOE-140 (0. 1mg to 1mg/kg, i.v.) 30min prior to SCI significantly enhanced the SCBF and reduced the BSCB disruption, edema formation, nNOS upregulation and cell injury. However, HOE-140 in doses ranging from 2mg to 5mg/kg, i.v. did not induce significant neuroprotection. These observations are the first to suggest that bradykinin B2 receptors play an important role in BSCB permeability, SCBF, edema formation, nNOS upregulation and cell injury following acute SCI, not reported earlier.

Inhibition of myosin light chain kinase reduces brain edema formation after traumatic brain injury

The role of the endothelial contractile apparatus in the process of brain edema formation after brain trauma is not characterized. Phosphorylation of myosin light chains by myosin light chain kinases (MLCK) activates endothelial contractile elements and results in a rearrangement of the cytoskeleton. This may enhance post-traumatic blood-brain barrier dysfunction. In order to investigate the role of the MLCK on brain edema formation and blood-brain barrier permeability after brain injury, mice were anesthetized and subjected to a controlled cortical impact (CCI). MLCK expression is significantly up-regulated after CCI with a maximum 12 h post-injury. Specific inhibition of MLCK by ML-7 resulted in a reduction of phosphorylation of myosin light chains and improved blood-brain-barrier integrity. Accordingly, ML-7 attenuated post-traumatic brain edema formation and intracranial hypertension 24 h after CCI. Prevention of brain edema formation did not translate into improved neurological outcome or reduced brain lesion. In conclusion, the results confirm that the endothelial contractile apparatus is activated by CCI and opens the endothelial barrier leading to vasogenic brain edema formation. Lack of neurological and histological improvement suggests that specific targeting of vasogenic brain edema at the endothelial level is not sufficient to limit secondary brain damage and has, therefore, to be combined with other potential neuroprotective strategies.

Midline-shift Corresponds to the Amount of Brain Edema Early After Hemispheric Stroke—An MRI Study in Rats

Vasogenic brain edema formation is a serious complication in hemispheric stroke. Its space-occupying effect can lead to midline-shift (MLS), cerebral herniation, and death. Clinical studies indicate that quantification of MLS can predict cerebral herniation and subsequent death at early time-points, even before clinical deterioration becomes apparent. The present experimental study was designed to determine the relation between MLS, absolute edema volume, lesion size, and clinical findings in a rat stroke model. Middle cerebral artery-occlusion was performed in 24 rats using the suture technique. Clinical evaluation and magnetic resonance imaging (MRI) (Bruker PharmaScan 7.0T) was performed 24 hours later. Lesion volume, the volume-increase within the affected hemisphere (%HEV), and MLS were quantified on T2-weighted images. The absolute increase of hemispheric water content (DeltaH2O) was determined in a subgroup using the wet-dry method (n=12). MLS correlated significantly with the total amount of brain edema (magnetic resonance imaging study: r=0.82; P<0.01; wet-dry analysis r=0.80; P<0.01). MLS correlated only moderately with T2-lesion volume (r=0.55; P<0.01). No significant correlation could be detected between MLS and clinical scores (r=0.26; P>0.05). MLS thus quantitatively reflects the amount of vasogenic brain edema within the affected hemisphere at early time-points. MLS quantification can be regarded as an easily assessable and valid global quantitative parameter for brain edema and thus might facilitate the surgical and nonsurgical management of edema in acute stroke patients.

Characterization of microvascular basal lamina damage and blood–brain barrier dysfunction following subarachnoid hemorrhage in rats

Vasogenic brain edema is one of the major determinants for mortality following subarachnoid hemorrhage (SAH). Although the formation of vasogenic brain edema occurs on the microvascular level by opening of endothelial tight junctions and disruption of the basal lamina, microvascular changes following experimental SAH are poorly characterized. The aim of the present study was therefore to investigate the time course of blood–brain barrier (BBB) dysfunction and basal lamina damage following SAH as a basis for the better understanding of the pathophysiology of SAH. SAH was induced in Sprague–Dawley rats by an endovascular filament. Animals were sacrificed 6, 24, 48, and 72 h thereafter ( n = 9 per group). Microvascular basal lamina damage was quantified by collagen type IV immunostaining. Western blotting was used to quantify collagen IV protein content and bovine serum albumin (BSA) extravasation as a measure for basal lamina damage and blood–brain barrier disruption, respectively. BSA Western blot revealed significant ( p < 0.05) BBB opening in the cerebral cortex ipsilateral to the hemorrhage beginning 6 h and peaking 48 h after SAH. Significant ( p < 0.05) basal lamina damage occurred with gradual increase from 24 to 72 h. Basal lamina damage correlated significantly with BBB dysfunction ( r = − 0.63; p = 0.0001). Microvascular damage as documented by collagen IV degradation and albumin extravasation is a long lasting and ongoing process following SAH. Due to its delayed manner microvascular damage may be prone for therapeutic interventions. However, further investigations are needed to determine the molecular mechanisms responsible for basal lamina degradation and hence damage of the microvasculature following SAH.

Transcellular transport as a mechanism of blood-brain barrier disruption during stroke.

It is well-known that ischemia causes disruption of the blood-brain barrier (BBB), which leads to the formation of vasogenic brain edema. One major mechanism of BBB opening is enhanced pinocytotic vesicle formation that may be induced after transient focal ischemia by several mechanisms, including nitric oxide production, release of neurotransmitters, inflammatory mediators and hemodynamic alterations. In the present study we sought to characterize the extent of pinocytosis in cerebral endothelium during both ischemia/reperfusion (I/R) and elevated intravascular pressure. Transient focal ischemia was induced for 1 hour with 24 hours of reperfusion using the filament occlusion model in male Wistar rats, after which occluded middle cerebral arteries (MCAs) were dissected and mounted on glass cannulas in an arteriograph chamber. This system allowed control over intravascular pressure, measurement of lumen diameter and perfusion with various tracers (Lucifer Yellow and horseradish peroxidase) for measurement of transcellular transport and quantification of pinocytosis using transmission electron microscopy. I/R was found to increase vesicle formation by 166% basolaterally without a change in vesicle formation apically compared to non-ischemic control MCAs at 75 mmHg (p less than 0.01). Similarly, an acute increase in pressure to 200 mmHg caused a 78% increase in apical pinocytosis (p less than 0.05) and a non-significant 42% increase basolaterally. These results were confirmed by permeability measurements using Lucifer Yellow and demonstrate that both I/R and acute elevations in intravascular pressure enhance cerebral endothelial cell pinocytosis. The increase in basolateral pinocytosis during ischemia suggests enhanced efflux mechanisms that may be transporting substances from brain to blood. In addition, since the enhanced pinocytosis after an increase in pressure occurred in isolated arteries in vitro without the influence of metabolic or neuronal factors, these findings demonstrate that elevated intravascular pressure is a primary stimulus for pinocytosis in cerebral endothelial cells.

Role of bradykinin B2 receptors in the formation of vasogenic brain edema in rats.

Bradykinin is a mediator of brain edema acting through B2 receptors. However, it is not known if bradykinin mediates the formation of cytotoxic or vasogenic brain swelling. To investigate this question we subjected rats to a cryogenic brain lesion over the left parietal cortex, a model well known to produce predominantly vasogenic brain edema. We inhibited bradykinin B2 receptors with the recently characterized nonpeptide B2 receptor antagonist, LF 16-0687. The animals were assigned to three groups (n = 10, each) receiving 10, or 100 microg/kg/min LF 16-0687 or vehicle (0.9% NaCl). Treatment started 15 min before trauma and was continued for 24 h. Another three groups of animals (n = 10, each) received 10 microg/kg/min LF 16-0687 starting 30 or 60 min after trauma or vehicle (0.9% NaCl) for 24 h. Animals were then sacrificed and swelling and water content of the brain were determined. In the vehicle treated group the traumatized hemisphere swelled by 9.3 +/- 1.1% as compared to the untraumatized contralateral side. Pretreatment with 10 microg/kg/min LF 16-0687 decreased brain swelling significantly to 6.4 +/- 1.3% (p < 0.05). Pre-treatment with 100 microg/kg/min was found to be less effective and did not result in a significant reduction of brain swelling (7.4 + 1.3%). Treatment with LF 16-0687 for 24 h (10 microg/kg/min) started 30 or 60 min after trauma did not reduce brain water content or hemispheric swelling. These results demonstrate that brain injury-mediated bradykinin production induces vasogenic brain edema by B2 receptor stimulation. Our findings further clarify the role of bradykinin in the pathophysiology of brain edema formation and confirm the therapeutic potency of bradykinin B2 receptor inhibition.

Glutathione homeostasis and leukotriene-induced permeability in human blood-brain barrier endothelial cells subjected to in vitro ischemia.

Ischemic alterations in the glutathione (GSH) redox system of the blood-brain barrier (BBB) may facilitate oxidative injury and formation of vasogenic brain edema. In this study, both the intra- and extracellular GSH contents of human cerebromicrovascular endothelial cells (HCEC) were reduced by 35% after exposing the cells to 4 h in vitro ischemia and 24 h-recovery. The intracellular/extracellular GSH ratio was not affected, indicating a constant rate of GSH efflux. The activities of the peroxide detoxifying enzymes, glutathione peroxidase and glutathione S-transferase, increased by 35%-50%, whereas the GSH regenerating enzyme, glutathione reductase, remained unchanged in ischemic HCEC. gamma-glutamyl transpeptidase (GGTP), a GSH catabolizing enzyme enriched in brain capillaries, was reduced by 30-50% in ischemic HCEC. The effect of in vitro ischemia on HCEC permeability was assessed by measuring sodium fluorescein clearance across a compartmentalized in vitro BBB model. Sodium fluorescein clearance across HCEC monolayers exposed to leukotriene C4 in the presence of the GGTP inhibitor, acivicin (1 microM), or after in vitro ischemia was increased by 60% and 30%, respectively, suggesting that oxidative stress and loss of GGTP may 'unmask' BBB permeabilizing actions of leukotrienes. These results indicate that oxidative stress and loss of GGTP activity in HCEC contribute to ischemic BBB disruption and vasogenic brain edema.

Regional differences in asphyxia- and reperfusion-induced cytotoxic and vasogenic brain edema formation in newborn pigs

Neonatal asphyxia may induce brain injuries. Development of cytotoxic and vasogenic edema was measured in frontal, parietal, occipital cortex, hippocampus, striatum, thalamus, internal capsule, cerebellum, pons, and medulla of newborn pigs in the following groups: control, asphyxia, and 3-h reperfusion. Water content was significantly (P < 0.05) increased in parietal cortex and hippocampus during asphyxia, and in cortical regions, hippocampus, and striatum during recovery. Asphyxia-reperfusion resulted in increased Na+ and Ca2+-, but decreased K+-concentrations in several brain regions. Blood-brain barrier permeability for sodium fluorescein (mw: 376) was significantly increased in all regions but internal capsule and medulla in asphyxia, and in each region during reperfusion. Evan's blue-albumin (mw: 67,000) efflux was unchanged in asphyxia, but significantly increased after reperfusion in all regions. Increased permeability was also demonstrated by confocal laser scanning microscopy. Edema formation in the early postasphyxial period in porcine brain corresponded to the specific patterns of cerebral damage in human neonates.

4-(2-Aminoethyl)benzenesulfonyl fluoride attenuates tumor-necrosis-factor-α-induced blood–brain barrier opening

The effect of serine protease inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF) was investigated on the prevention of tumor-necrosis-factor-α (TNF-α)-induced blood–brain barrier opening. TNF-α (10,000 IU) was injected intracarotidly to newborn pigs pretreated with 0, 2.4, 4.8, 9.6 and 19.2 mg/kg AEBSF ( n=6 in each group). AEBSF dose-dependently inhibited the TNF-α-induced increase in the blood–brain barrier permeability for sodium fluorescein (MW=376) in all of the five brain regions examined, while only 19.2 mg/kg AEBSF could significantly ( P<0.05) decrease the change in Evan's blue-albumin (MW=67,000) transport in two regions. In conclusion, AEBSF attenuates vasogenic brain edema formation.

Cerebral ischemia reperfusion-induced vasogenic brain edema formation in rats: effect of an intracellular histamine receptor antagonist.

Resuscitation in pediatric emergency and some neurological interventions may result in ischemia reperfusion-induced cerebral injuries. Histamine is one of the well established mediators of cerebral swelling and H1- and H2-receptor antagonists could prevent the development of ischemic brain edema. In the present study, time-dependent changes in the blood-brain barrier (BBB) permeability were investigated in the cerebral cortex of male Wistar rats 1, 2, 4, 8, and 16 h after the beginning of post-ischemic reperfusion. Cerebral ischemia-reperfusion evoked by the 4-vessel occlusion model resulted in significant (p < 0.05) elevations in BBB permeability for albumin, but not for sodium fluorescein. Pre-treatment with a new intracellular histamine receptor antagonist could not prevent ischemic brain edema formation in that model. We conclude that experimental studies could help us to reveal the therapeutic role of histamine receptor antagonists during ischemic brain edema.

Experimental acute pancreatitis results in increased blood–brain barrier permeability in the rat: a potential role for tumor necrosis factor and interleukin 6

Pancreatic encephalopathy is a severe complication of acute pancreatitis. Proinflammatory cytokines may play a role in the development of multi-organ failure during pancreatitis. In the present study, we measured the changes in the blood–brain barrier (BBB) permeability concomitantly with the determination of serum tumor necrosis factor (TNF) and interleukin-6 (IL-6) levels in rats before, as well as 6, 24 and 48 h after the beginning of intraductal taurocholic acid-induced acute pancreatitis. Cytokine concentrations were measured in bioassays with specific cell lines (WEHI-164 for TNF and B-9 for IL-6), while the BBB permeability was determined for a small (sodium fluorescein, molecular weight (MW) 376 Da), and a large (Evans' blue-albumin, MW 67 000 Da) tracer by spectrophotometry in the parietal cortex, hippocampus, striatum, cerebellum and medulla of rats. The serum TNF level was significantly ( P<0.05) increased 6 and 24 h after the induction of pancreatitis, while the IL-6 level increased after 24 and 48 h. A significant ( P<0.05) increase in BBB permeability for both tracers developed at 6 and 24 h in different brain regions of animals with acute pancreatitis. We conclude that cytokines, such as TNF and IL-6, may contribute to the vasogenic brain edema formation during acute pancreatitis.

Intracarotid histamine administration results in dose-dependent vasogenic brain oedema formation in new-born pigs.

Intracarotid histamine administration results in dose-dependent vasogenic brain oedema formation in new-born pigs.

Endothelial Acid Phosphatase May Participate in the Histamine-Induced Vasogenic Brain Oedema Formation in Newborn Pigs 137

Endothelial Acid Phosphatase May Participate in the Histamine-Induced Vasogenic Brain Oedema Formation in Newborn Pigs 137

Intracarotid tumor necrosis factor-α administration increases the blood-brain barrier permeability in cerebral cortex of the newborn pig: quantitative aspects of double-labelling studies and confocal laser scanning analysis

Tumor necrosis factor-α (TNF-α) plays a crucial role in the pathogenesis of the central nervous system infections. The aim of the present study was to analyze quantitatively the changes in the blood-brain barrier (BBB) permeability after the intracarotid injection of TNF-α. Recombinant human TNF-α was injected into the left internal carotid artery of anesthetized newborn pigs ( n = 48) in the doses of 0, 1000, 10 000 and 100 000 IU, respectively. Before, as well as 1, 2, 4, 8, and 16 h after the challenge, the extravasation of a small (sodium fluorescein (SF), mw 376), and a large (Evan's blue-albumin (EBA), mw 67 000) tracer was determined concomitantly by spectrophotometry in the cerebral cortex of the animals. There was a time- and dose-dependent increase in BBB permeability both for SF and EBA; however, significant ( P < 0.05) BBB opening for albumin only developed 2 h after the challenge. In the morphological study the same excitable tracers, identical experimental protocol and groups were used. Cryostat sections of brain tissue were viewed for optical sectioning with a confocal laser scanning microscope equipped with an argon/krypton ion laser. A diffuse BBB opening for SF and a moderate perivascular extravasation for EBA were found in the cortices of TNF-α-treated animals. We conclude that significant increases in intravascular TNF-α-concentration during neonatal infections may result in vasogenic brain edema formation.

INTRACAROTID HISTAMINE ADMINISTRATION RESULTS IN A DOSE-DEPENDENT VASOGENIC BRAIN EDEMA FORMATION IN NEWBORN PIGS. 1381

Histamine, a vasoactive mediator, may play a role in the pathogenesis of neonatal hypoxic-ischemic cerebral injuries. We have previously found that histamine accumulated in brain compartments during asphyxia (Kovacset al. 1995 Neurosci Lett 195:25), and antihistamines prevented brain edema formation (Dux et al. 1987 Neuroscience 22:317) in asphyxiated newborn pigs. The aim of the study was to reveal the changes in the blood-brain barrier (BBB) permeability after the intracarotid injection of histamine. Thirty newborn pigs (4-8 h; 1,180-1,530 g; ketamine anesthesia, 10 mg × kg-1) of either sex were included in the study. The left internal carotid artery of the animals was catheterized through the external branch, and histamine diluted in 1.0 mL isotonic saline was injected into the vessel in the following doses: 0, 10-6, 5×10-6, 10-5, 5×10-5, 10-4 M, respectively, through 1 min in 6 groups of animals (n=5 in each). Then the external carotid artery was ligated, and 1 h after the challenge BBB permeability was determined concomitantly for a small (sodium fluorescein, SF, 376 Da) and a large (Evans blue/albumin, EBA, 67 kDa) tracer (2%, 5 mL×kg-1, 30 min circulation time for both dyes) in frontal, parietal and occipital cortex, hippocampus, and periventricular white matter both on left and right sides. After the removal of the intravascular dyes by perfusion, the BBB permeability for both tracers was quantified by fluorescence spectrophotometry, the wavelengths for excitation and emission were 440 nm and 525 nm for SF; and 620 nm and 680 nm for EBA, respectively. Histamine injection in doses higher than 10-6 M resulted in a significant (P<0.05; Kruskal-Wallis one way ANOVA on ranks followed by Dunn's test) increase in BBB permeability for both tracers in each brain region examined. Changes in the left hemisphere were more intense (P<0.05) than those in the right one after the doses of 5×10-6 and 10-5 M in each region, while 10-4 M histamine administration induced similar edema in both sides. We conclude that intracarotid histamine infusion results in a dose-dependent vasogenic brain edema formation in newborn pigs.