Cold-induced Brain Edema Research Articles

Effect of melatonin on cerebral edema in rats.

Melatonin (5-methoxy-N-acetyltrypamine), a chemical naturally produced in the pineal gland, has been suggested to be a free radical scavenger and an antioxidant. In the present study, the effect of melatonin on cold-induced brain edema was evaluated by determination of cerebral water content, blood-brain barrier permeability, and areas of infarct; the effects were also studied histopathologically. Brain edema was produced in rats by creating a lesion via cortical freezing. Animals were separated into four groups: sham-operated (craniectomy only); control (cold injury); sham-vehicle (cold injury plus saline); and melatonin treatment (cold injury plus melatonin). Melatonin was administered (50 mg/kg intraperitoneally) 15 minutes after the cold injury was induced. Twenty-four hours later, tissue samples from the core, from the periphery of the cold-injured hemisphere, and from the contralateral hemisphere symmetrical to the cold injury were obtained. Melatonin treatment reduced edema (mean +/- standard deviation; 86.22 +/- 1.54% in the control group versus 80.78 +/- 2.76% in the melatonin treatment group, P < 0.001) and blood-brain barrier permeability (45.34 +/- 2.75% in the control group versus 38.26 +/- 3.40% in the melatonin treatment group, P < 0.001) at the periphery of cold injury. Area of infarct reduced from 5.84 +/- 0.58% in the control group to 3.30 +/- 0.89% in the melatonin treatment group (P < 0.001). The effect of melatonin was also confirmed histopathologically. Melatonin was found to be neuroprotective in instances of cold-induced brain edema. Thus, melatonin may be a valuable therapeutic agent in the treatment of cerebral edema.

Treatment of brain edema with a nonpeptide arginine vasopressin V1 receptor antagonist OPC-21268 in rats.

Recent experimental evidence suggests that centrally released arginine vasopressin plays a significant role in brain capillary water permeability as well as in pathogenesis of vasogenic brain edema. The purpose of this study was to examine the effects of orally administered OPC-21268, a nonpeptide arginine vasopressin V1 receptor antagonist, on cold-induced brain edema in rats. Cold brain injury was induced for 1 minute in 140 rats. Treatment with OPC-21268, at dosages of 100 mg (n = 20), 200 mg (n = 20), and 300 mg/kg (n = 15), or with saline (n = 17) was started 1 hour after the induction of cold injury and was continued every 8 hours for 24 hours. Two percent Evans blue in saline (1 ml/kg) was administered intravenously before cold injury in another group of rats, 15 of which were saline-treated and 55 of which were OPC-21268-treated at the above dosages. After 24 hours, brain tissue water and electrolytes, brain tissue swelling, blood-brain barrier permeability to Evans blue, and plasma electrolytes and osmolality were determined. Compared with the saline-treated group, OPC-21268 treatment at the dosages of 200 and 300 mg/kg significantly reduced brain water content in both hemispheres (P<0.01). Swelling of the traumatized hemispheres was also significantly reduced at 200 and 300 mg/kg dosages (P<0.05). Brain tissue sodium content was significantly reduced at the dosage of 300 mg/kg (P<0.05). Blood-brain barrier permeability to Evans blue was significantly decreased in a dose-dependent manner compared with the saline-treated group (P<0.01). No significant changes were observed in other parameters. Our results indicate that OPC-21268 predominantly exerts a protective effect in areas where the maximum amount of blood-brain barrier breakdown occurs, and it is effective in the treatment of cold-induced vasogenic brain edema.

The nature of antioxidant defense mechanisms: a lesson from transgenic studies.

Reactive oxygen species (ROS) have been implicated in the pathogenesis of many clinical disorders such as adult respiratory distress syndrome, ischemia-reperfusion injury, atherosclerosis, neurodegenerative diseases, and cancer. Genetically engineered animal models have been used as a tool for understanding the function of various antioxidant enzymes in cellular defense mechanisms against various types of oxidant tissue injury. Transgenic mice overexpressing three isoforms of superoxide dismutase, catalase, and the cellular glutathione peroxidase (GSHPx-1) in various tissues show an increased tolerance to ischemia-reperfusion heart and brain injury, hyperoxia, cold-induced brain edema, adriamycin, and paraquat toxicity. These results have provided for the first time direct evidence demonstrating the importance of each of these antioxidant enzymes in protecting the animals against the injury resulting from these insults, as well as the effect of an enhanced level of antioxidant in ameliorating the oxidant tissue injury. To evaluate further the nature of these enzymes in antioxidant defense, gene knockout mice deficient in copper-zinc superoxide dismutase (CuZnSOD) and GSHPx-1 have also been generated in our laboratory. These mice developed normally and showed no marked pathologic changes under normal physiologic conditions. In addition, a deficiency in these genes had no effects on animal survival under hyperoxida. However, these knockout mice exhibited a pronounced susceptibility to paraquat toxicity and myocardial ischemia-reperfusion injury. Furthermore, female mice lacking CuZnSOD also displayed a marked increase in postimplantation embryonic lethality. These animals should provide a useful model for uncovering the identity of ROS that participate in the pathogenesis of various clinical disorders and for defining the role of each antioxidant enzyme in cellular defense against oxidant-mediated tissue injury.

Nitric oxide synthase immunoreactivity related to cold-induced brain edema

To determine the relationship between brain edema and the expression of nitric oxide synthase (NOS)I we immunohistochemically studied the distribution and level ofNOS in rat brain cold injury model. Vasogef]ic brain edema was produced by cortical freezing lesion. NOS immunohistochemical studies were performed 4 and 8 hI 11 31 51 71 14 and 21 days after injury. In control normotensive ratsl immunoreactivity for NOS was observed in scattered neuronal cells as reported previouslYI but there was no reactivity in glial cells. In the present study in the cold injury modell howeverl fibrinogen staining showed extravasated plasma fluid extending to the white matter contralateral to the site of cold injury. NOS immunoreactivity was observed in most reactive astrocytes and a proportion of the microglial cells and macrophages in the white matter not only just beneath the area of cold injury but also in the contralateral side. The nerve cells in the edematous region scarcely showed additional immunoreactivity for NOS. The distribution of increased NOS relatively corresponded with the sites of extravasated plasma fluid demonstrated by fibrinogen staining. Electron microscopically, NOS was observed in astrocytes along the rough endoplasmic reticulum suggesting that NOS was produced in the cells and not taken up from thersurroundings. Based on these findings, we postulate that brain edema and the simultaneously generated free radicals or some extravasated plasma components may induce expression of NOS in the reactive cells, and that the NO thus generated may be involved in the development of diffuse degeneration of the white matter which accompanies brain edema. [Neural Res 1998; 20: 637–642]

Protective effects of AVS 1,2-bis (nicotinamido)-propane, against cold-induced brain edema: magnetic resonance imaging and spectroscopy

It was hypothesized that AVS 1,2-bis(nicotinamide)-propane, a free radical scavenger, could potentially be useful for the treatment of brain edema. Vasogenic brain edema was produced by freezing brain regions in 36 rats that had been treated with either AVS or saline. The efficacy of treatment was analyzed using proton magnetic resonance imaging ( 1H MRI) and proton magnetic resonance spectroscopy ( 1H MRS) of perchloric acid tissue extracts. T2-weighted MRI was obtained at 1 and 24 h after freezing. For 1H MRS studies, rats were killed using liquid nitrogen and the extracted metabolites from the frozen hemispheres analyzed. 1H MRI showed the edema lesion that indicated a region of a high signal intensity gradually extended and increased in intensity. Suppression of the edema development was observed in the AVS-treated group. Shortly after injury, the levels of acetate and lactate rapidly rose. Subsequently, the amino acid of alanine was also increased and N-acetyl aspartate and glutamine were markedly depressed. In AVS-treated rats, increases of lactate and alanine, and decreases of N-acetyl aspartate were statistically significant. We concluded that AVS is valuable for the treatment of vasogenic brain edema using these MR techniques.

Protective effect of arginine vasopressin (AVP) release inhibitor on cold-induced brain edema in rats

Protective effect of arginine vasopressin (AVP) release inhibitor on cold-induced brain edema in rats

Cold-induced brain edema in mice. Involvement of extracellular superoxide dismutase and nitric oxide

The role of extracellular superoxide in the pathogenesis of vasogenic edema was studied using transgenic mice expressing a 5-fold increase in extracellular superoxide dismutase (EC-SOD) activity in their brains. Increased EC-SOD expression offered significant protection against edema development after cold-induced injury (44% less edema than nontransgenic littermates, p < 0.05). Since iron may contribute to vasogenic edema by catalyzing the production of hydroxyl radical from superoxide and hydrogen peroxide, the effects of the chelator deferoxamine were studied. Deferoxamine reduced edema formation after cold-induced injury (43% less edema than controls, p < 0.05); however, treatment with iron-saturated deferoxamine also reduced edema development in mice (32-48% less edema, p < 0.05). This suggested that the protection offered by deferoxamine was independent of its ability to chelate iron. An iron-independent mechanism by which superoxide can contribute to vasogenic edema is via reaction with nitric oxide to produce the potentially toxic peroxynitrite anion, which is also scavenged by deferoxamine. Mice treated with an inhibitor of nitric oxide synthase were protected against cold-induced edema (37% less edema, p < 0.05). EC-SOD transgenic mice received no additional protection by inhibition of nitric oxide synthesis, supporting this novel alternative mechanism of edema formation.

Inhibition of oxygen toxicity by targeting Superoxide dismutase to endothelial cell surface

Since enzymes that degrade reactive oxygens, such as Superoxide dismutase (SOD), are significantly lower in plasma than in intracellular compartments, cell surface membranes should be protected against hazardous oxygens particularly when animals are challenged with oxidative stress. To minimize oxygen toxicity on endothelial cell surface, a fusion gene consisting of cDNA coding human Cu 2+/Zn 2+-SOD and heparin-binding peptide was constructed and expressed in yeast. The resulting enzyme (HB-SOD) bound to a heparin-Sepharose column and cultured endothelial cells; binding was inhibited either by high NaCl concentrations or heparin. When injected intravenously, HB-SOD predominantly bound to vascular endothelial cell surface. Carrageenin-induced paw edema and cold-induced brain edema of the rat were markedly inhibited by a single dose of HB-SOD. These results suggest that Superoxide radical and/or its metabolite(s) occurring at or near the outer surface of vascular endothelial cells might play a critical role in the pathogenesis of vasogenic edema.

Protective effect of the iron chelator deferoxamine on cold-induced brain edema.

Oxygen free radicals such as superoxide radical and iron-catalyzed hydroxyl radical generated by the superoxide system have been implicated in the genesis of brain edema. Therefore, deferoxamine (DFO), an iron chelator, could potentially be used to treat brain edema. To examine this hypothesis, vasogenic brain edema was produced in 48 cats by a cortical freezing lesion. The animals were separated into three groups: Group 1 comprised 14 cats that received no DFO and were sacrificed at 6 or 24 hours; Group 2 consisted of 12 cats that were treated with DFO (50 mg/kg/ml, intravenously) at 15 minutes before the lesion was made and 60 minutes later and were sacrificed at 6 or 24 hours; and Group 3 included 12 cats that were treated with DFO (50 mg/kg/ml, intravenously) at 15 minutes after the lesion was produced and 60 minutes later and were sacrificed at 6 or 24 hours. The effect of DFO on arterial blood pressure was also studied in the remaining 10 cats. Brain water content in eight sampling areas was measured by the specific gravity method. Blood-brain barrier disruption was assessed by spread of Evans blue dye with planimetry. Specific gravity values at 6 and 24 hours were significantly higher in Group 2 than in Group 1 animals. Areas of Evans blue dye extravasation at 6 and 24 hours were significantly reduced in Group 2 relative to Group 1. Group 3 cats showed improvement in specific gravity values and Evans blue extravasation at 6 hours, but not at 24 hours. The iron chelator DFO prevented early development of brain edema; thus, this oxygen free radical scavenger may provide a foundation for a new therapy for brain edema.

Comparative study of different iron-chelating agents in cold-induced brain edema

Increasing numbers of reports demonstrate the importance of iron and oxygen free radicals in brain injury and brain edema. We investigated the protective effects of three different ferric and ferrous iron-chelating agents on cold-induced brain edema. Vasogenic brain edema was produced by a cortical freezing lesion. Thirty-eight cats were separated into five groups: Group 1 (N = 8): normal control group without lesion; Group 2 (N = 8): untreated group; Group 3 (N = 8): deferoxamine (extracellular and intracellular ferric iron chelator)-treated group; Group 4 (N = 8): 2,3-dihydroxybenzoic acid (extracellular ferric iron chelator)-treated group; and Group 5 (N = 6): 2,2-bipyridine (intracellular ferrous iron chelator)-treated group. In Groups 3, 4, and 5, each agent was administered intravenously 15 minutes before lesion production and 60 minutes later. Animals in Groups 2, 3, 4, and 5 were killed 6 hours after lesion production. Brain water content in 8 sampling areas was measured by the specific gravity method. Blood-brain barrier disruption was assessed by the spread of Evans blue dye measured by planimetry. Brain water contents and Evans blue dye extravasated areas were significantly reduced in Groups 3 and 5 in comparison to Groups 2 and 4. These data suggest that both ferrous and ferric iron-chelating agents, which can penetrate the cell membrane and, presumably, act intracellularly, are effective in reducing cold-induced brain edema. (Neurosurgery 24:820-824, 1989)

Effect of a superoxide dismutase derivative on cold-induced brain edema

Although the involvement of reactive oxygen species has been suggested in the pathogenesis of brain edema, direct evidence supporting this concept is lacking. To elucidate a critical role of oxygen radicals, effect of a superoxide dismutase (SOD) derivative that circulated bound to albumin with a half-life of 6 h on the occurrence of cold-induced brain edema was studied in the rat. When animals were challenged with brain injury by applying a liquid-nitrogen-cold probe to one side of the cerebral hemisphere over the bony skull for 20 s, the vascular permeability of the underlying tissue increased significantly and unilateral brain edema occurred as determined by the accumulation of intravenously injected Evan's blue and the increase in brain weight. Intravenous administration of the SOD derivative markedly suppressed the increase in vascular permeability and the occurrence of brain edema, particularly at their early stages. These and other results suggest that superoxide anion and/or its metabolite(s) might play a critical role in the pathogenesis of traumatic brain injury.

Pathological and biochemical studies of unilateral cold induced brain edema in the rat.

This study was carried out to clarify the biochemical changes in the cold injured brain and their relationship to pathological changes. The cold lesion was produced by application of a cryoprobe containing liquid nitrogen to the exposed left temporal surface for 1 minute in rats anesthetized with a halothane and oxygen gas mixture. The brain edema developed by this procedure was localized in one hemisphere. The animals were guillotined at scheduled times after the cold injury. The brains were rapidly removed and divided exactly between the two hemispheres. Changes in specific gravity of the brain tissue were measured by the dry-weight method until 4 weeks after the injury. Hematoxylin-eosin and Kliiver-Barrera stains were applied to pathological specimens. Free amino acid and uric acid levels were measured chronologically by using Iriyama's method. Catecholamine levels were analyzed by using high-performance liquid chromatography with electrochemical detection. Water content in the injured hemisphere reached a peak level at 12 hours after the injury, then decreased gradually, and entered the normal range at 1 week after the injury. This results was similar to the previous report. Multiple small hemorrhagic lesions were disclosed 2 hours after the injury. This suggests that a mechanism similar to hemorrhagic infarction might play a role in the development of cold injury. Essential amino acids were increased in the injured hemisphere, while those in the contralateral side remained within normal ranges. This result suggests that, in the injured hemisphere, there was not only nonutilization of the essential amino acids but also disturbance of the blood brain barrier, and that the aerobic glycolytic pathway was maintained normally in the contralateral hemisphere. Norepinephrine and dopamine were lowered, while tyrosine was increased in the early stage of cold injury. This suggests impairment of the catecholamine synthesis followed by nonutilization of catecholamine precursors. Uric acid level was increased immediately after the injury, especially on the injured side, and lowered to near baseline level at 4 weeks after the insult. Although biosynthesis of uric acid in the brain is not fully understood, it seems to be a fine parameter of brain damage.

Effect of vasopressin on cold-induced brain edema in cats.

Centrally released arginine vasopressin (AVP) has been implicated in the regulation of intracranial pressure (ICP) and brain water, and is elevated in the cerebrospinal fluid (CSF) of some patients with pseudotumor cerebri or subarachnoid hemorrhage. The authors have examined the relationship of AVP levels in CSF to ICP and brain water content in three experimental groups of cats with and without cold-induced vasogenic edema. With the cats under general anesthesia, a cold lesion was made and cannulas were placed in the cisterna magna, lateral ventricle, and aorta. Subsequent central and systemic measurements were made while the animals were awake and free-roaming. In Experiment 1, endogenous AVP levels in CSF were measured every 12 hours over a 48-hour period by radioimmunoassay in cats with sham craniotomy, mild edema, or moderate edema; no significant difference was found between groups although a diurnal variation was seen (range 2 to 18 pg/ml). In Experiment 2, either carrier solution or AVP, in doses of 1.5 or 30 ng, was administered via a lateral ventricle every 2 hours over 24 hours in unlesioned cats. In Experiment 3, cats received 2 or 35 ng of carrier solution or AVP in a similar manner, but coupled with a cold lesion. The CSF AVP levels ranged from an average of 100 to 681 pg/ml and 1.4 to 11.9 ng/ml in the two dose groups in both experiments. Neither the low nor the high dose had an effect on brain water content in normal white matter (Experiment 2), but both doses increased brain water content in edematous white matter (p less than 0.05 in Experiment 3), as determined by wet and dry weight measurements of standardized pieces of white matter. The ICP was decreased by high-dose AVP in normal cats (p less than 0.01 at 24 hours), but in lesioned cats was unchanged by low-dose and increased by high-dose AVP (p less than 0.05 at 18 hours). The authors conclude that pharmacological doses of central AVP facilitate the production of vasogenic edema.

The effect of cold-induced brain edema on cerebrospinal fluid formation rate.

The net contribution of vasogenic brain edema to cerebrospinal fluid (CSF) formation was studied by ventriculocisternal perfusion. Individual cats were perfused both before and 2 1/2 hours after a severe cold-induced injury to the cerebral cortex, and the results were compared. Although the edema had occupied the larger part of the hemispheric white matter and bordered the lateral ventricle, a decrease rather than an increase in CSF formation rate was observed. This decrease was related to a decrease in the cerebral perfusion pressure by a regression equation that was not affected by the cold injury.

The effects of cold-induced brain edema and white-matter ischemia on the somatosensory evoked response.

The electrophysiological effects of cold-lesion edema and white-matter ischemia were studied in cats by reference to the short-latency somatosensory evoked response. The primary cortical waves were found to be considerably delayed following a period of white-matter ischemia; hosever, cold-lesion edema appeared to have no significant effect on the evoked response. The authors conclude that vasogenic edema does not interfere with axonal functioning by an ischemic mechanism.

Lactate dehydrogenase and creatine kinase activities in isolated edema fluid and peripheral blood in cold-induced brain edema.

A study of the alterations in lactate dehydrogenase and creatine kinase isoenzyme patterns in isolated grey and white matter edema fluid and in peripheral blood is described with a view to possible clinical use in severe brain-injury. The breakdown of the blood-brain barrier, caused by the infliction of a cold injury to the cerebral cortex of cats, resulted in a shift in the LD isoenzyme distribution in favour of the faster moving fractions and the appearance of brain-type CK in the peripheral blood. Total lactate dehydrogenase activity demonstrated no statistical significant changes during the experiment and total creatine kinase showed only slight increased values in the samples collected simultaneously with the infliction of a cold lesion. This strongly suggests that measurements of these parameters in peripheral blood are of little value as indicators of brain damage. Alterations in isoenzyme patterns observed in edema fluids are reflected in peripheral blood. The presence, therefore, of brain-type creatine kinase accompanied by a relative high amount of lactate dehydrogenase H-sub unit in peripheral blood, can be considered as adequate indices of severe brain damage.

The electroencephalogram and intracranial pressure in cold-induced brain edema in the cat

In 30 cats the EEG was recorded before and after a right parietal cold trauma to the brain and evaluated with a computer. Over both hemispheres the epidural pressure was registered with miniaturized transducers. We recorded the ventricular pressure as well as the arterial and central venous pressure after catheterization. Before the trauma there were distinct fluctuations in the EEG power. Posttraumatically the EEG power diminished immediately at all frequencies. After 15 to 30 min there was an “α activation” in 50% of the animals. The power of the α band exceeded the initial value. Although the intracranial pressure rose rapidly, a recovery of the EEG occurred in the majority of animals, but mainly over the left, nontraumatized hemisphere. A progressive flattening of the EEG was also found over the left hemisphere 1.5 to 4 h after the trauma. ϑ-δ waves occurred only inconstantly. If the cerebral perfusion pressure became less than 50 mm Hg, the EEG rapidly became isoelectric. The diminution of the EEG power immediately after the trauma and even in the left brain indicates functional disturbances. A primary disturbance of metabolism is not to be assumed. The activation of the EEG after trauma is to be regarded as a stress symptom, and its absence in 50% of the animals indicates a different functional responsiveness of ergotropic diencephalic-mesencephalic centers. The later increase in δ waves is caused by raised intracranial pressure and secondary disturbances of subcortical structures due to edema.

The effect of intracerebral ouabain administration on the composition of edema fluid isolated from cats with cold-induced brain edema

Brain edema fluid was collected from cats with a freezing lesion in the left parietal cortex by the insertion into the brain of needles containing nylon wicks and connected to polyethylene tubes. The edema fluid samples which accumulated in the polyethylene tubes were regularly analyzed for Na + and K + content, colloid osmotic pressure, lactate dehydrogenase and creatine phosphokinase activity, and 99mTc-albumin radioactivity; the albumin tracer being introduced intravenously at the time of cold-injury. One series of cats received an intracerebral injection of ouabain solution, the control series an intracerebral injection of saline, at 100 min after the cold-injury. The ouabain injection was followed by an increase of K + content, LDH and CPK activities but a decrease of Na + concentration in the edema fluid, attributable to a concentration of solutes in the edema fluid as presumably water and Na + were shifted into the cells and hence the extracellular space was reduced.

Changes of electrical impedance in edematous cat brain during hypoxia and after intracerebral ouabain injection

Using an alternating current of 750 Hz, electrical impedance was measured at various depths in the white matter of the brain of cats previously subjected to a freezing injury of the cerebral cortex. The cold-induced brain edema resulted in a decrease of the impedance corresponding to an enlargement of the tissue extracellular space in which the edema fluid accumulated. Subsequent induction of hypoxia or intracerebral injection of ouabain resulted in an increase of the impedance; the increase was considered to be caused by a reduction of the extracellular space as fluid was shifted into the cellular elements.

Composition of isolated edema fluid in cold-induced brain edema

Edema fluid isolated from cats with cold-induced brain edema was subjected to analysis of electrolyte content, enzyme activities, colloid osmotic pressure and the radioactivity of intravenously injected 99mTc-labeled albumin. The findings corroborate the essential features of vasogenic edema, such as its origin from the blood plasma, its rapid propagation into the white matter of the brain as contrasted with the delayed spread into gray matter, and its contribution to composition of cerebrospinal fluid. Moreover, the elevated activities of cellular enzymes and K+ content of edema fluid point to the admixture with cellular contents due to the freezing damage.