Activation of liver X receptor reduces global ischemic brain injury by reduction of nuclear factor-kappaB.

Recent studies have found that liver X receptors (LXRs) agonists decrease brain inflammation and exert neuroprotective effect. The aim of this study was to examine the mechanisms of action of liver X receptor agonist GW3965 against brain injury following global cerebral ischemia in the rat. The 48 male SD (Sprague-Dawley) rats were randomly partitioned into three groups: sham, global ischemia (4-vessel occlusion for 15 min; 4VO) treated with vehicle and global ischemia treated with GW3965 (20 mg/kg, via i.p. injection at 10 min after reperfusion). The functional outcome was determined by neurological evaluation at 24 h post ischemia and by testing rats in T maze at 3 and 7 days after reperfusion. The rats' daily body weight, incidence of seizures and 72 h mortality were also determined. After Nissl staining and TUNEL in coronal brain sections, the numbers of intact and damaged cells were counted in the CA1 sector of the hippocampus. The expression of phosphorylated inhibitor of kappaB (p-IkappaBalpha), nuclear factor-kappaB (NF-kappaB) subunit p65, and cyclo-oxygenase-2 (COX-2) were analyzed with Western blot at 12 h after reperfusion. GW3965 tended to reduce 72 h mortality and the incidence of post-ischemic seizures. GW3965-treated rats showed an improved neuronal survivability in CA1 and a significant increase in the percentage of spontaneous alternations detected in T-maze on day 7 after ischemia. GW3965-induced neuroprotection was associated with a significant reduction in nuclear translocation of NF-kB p65 subunit and a decrease in the hippocampal expression of NF-kB target gene, COX-2. LXR receptor agonist protects against neuronal damage following global cerebral ischemia. The mechanism of neuroprotection may include blockade of NF-kappaB activation and the subsequent suppression of COX-2 in the post ischemic brain.

Effects of superoxide dismutase and catalase derivates on intracerebral hemorrhage-induced brain injury in rats.

The use of exogenous superoxide dismutase (SOD) and catalase (CAT) has been previously evaluated against various reactive oxygen species-mediated brain injuries, especially those associated with ischemia/ reperfusion. In this study, we investigated effects of these enzymatic antioxidants on intracerebral hemorrhage (ICH)-induced brain injury. A total of 65 male Sprague-Dawley rats (300-380 g) were divided into a sham group, an untreated ICH group, 3 groups of ICH rats treated with lecithinized SOD (PC-SOD) at doses of 0.1, 0.3, and 1 mg/kg, and a group treated with polyethylene glycol conjugated CAT (PEG-CAT) at a dose of 10,000 U/kg. An additional group of ICH rats received a combination of PC-SOD (1 mg/kg) and PEG-CAT (10,000 U/kg). ICH was induced by collagenase injection. All drugs were administered intravenously immediately after ICH induction. Brain injury was evaluated by scoring neurological function and measuring brain edema at 24 h after ICH induction. Our results demonstrated that ICH caused significant neurological deficit associated with remarkable brain edema. Treatment with PC-SOD, PEG-CAT, or PC-SOD in combination with PEG-CAT did not reduce brain edema or neurological deficit after ICH. We conclude that intravenously administered PC-SOD and/or PEG-CAT do not reduce brain injury in the collagenase-induced ICH rat model.

Deficiency of CD18 gene reduces brain edema in experimental intracerebral hemorrhage in mice.

Experimental studies of intracerebral hemorrhage (ICH) point toward leukocytes as a major contributor to ICH-induced brain injury. Leukocyte and endothelial cell adhesion molecules are responsible for injurious neutrophil-endothelial cell interactions in vasculature. Since deficiency of leukocyte-expressed CD18 protects against ischemia-reperfusion injury, we hypothesized that such deficiency may have similar effect in ICH-induced injury. Our aim was to investigate whether CD18 deficiency affords neuroprotection by decreasing ICH-induced brain injury, thereby improving neurological function and reducing mortality. A total of 20 males wild-type CDI8+/+ mice and 12 CD18-/- knockout mice were used in our study. ICH was induced by collagenase injection. Mortality, neurological function, and brain edema were measured at 24h after ICH. Data were analyzed by ANOVA, Chi-square, and Student t-test. Differences of p < 0.05 were considered statistically significant. Our study showed that the increase in brain water content caused by ICH was significantly smaller in CD18 knockout mice compared with wild-type mice (p < 0.05, Student t-test). This result correlated with a tendency toward improvement of neurological function and a decrease in mortality. We conclude that CD18 deficiency significantly reduces brain edema after ICH, which corresponds with a trend toward reduction in neurological deficit and mortality.

Effect of amantadine sulphate on intracerebral hemorrhage-induced brain injury in rats.

Recent studies have shown that amantadine, an uncompetitive N-methyl-d-aspartate receptor antagonist and dopamine agonist, is effective for the treatment of various cerebral disorders and causes relatively mild side effects. In this study, we investigated whether administration of amantadine will provide a neuroprotective effect in the intracerebral hemorrhage (ICH) rat model. A total of 15 male Sprague Dawley rats (300-380 g) were divided into sham, ICH-untreated, and ICH-treated with amantadine sulphate groups. ICH was induced by collagenase injection. Total dose 6 mg/kg of amantadine sulphate was divided into 3 injections and administered intraperitoneally at 1, 8, and 16 h after ICH. Brain injury was evaluated by investigating neurological function and brain edema at 24 h after ICH. Our data demonstrates that ICH caused significant neurological deficit associated with marked brain edema. Amantadine did not reduce brain injury after ICH; neurological function and brain edema in the treated group were not different from those of the untreated group. We conclude that amantadine sulphate does not offer neuroprotection in acute stage of experimental ICH-induced brain injury.

Dynamic production of hypoxia-inducible factor-1alpha in early transplanted islets.

More than half of transplanted beta-cells undergo apoptotic cell death triggered by nonimmunological factors within a few days after transplantation. To investigate the dynamic hypoxic responses in early transplanted islets, syngeneic islets were transplanted under the kidney capsule of balb/c mice. Hypoxia-inducible factor-1alpha (HIF-1alpha) was strongly expressed at post-transplant day (POD) 1, increased on POD 3, and gradually diminished on POD 14. Insulin secretion decreased on POD 3 in association with a significant increase of HIF-1alpha-related beta-cell death, which can be suppressed by short-term hyperbaric oxygen therapy. On POD 7, apoptosis was not further activated by continually produced HIF-1alpha. In contrast, improvement of nerve growth factor and duodenal homeobox factor-1 (PDx-1) production resulted in islet graft recovery and remodeling. In addition, significant activation of vascular endothelial growth factor in islet grafts on POD 7 correlated with development of massive newly formed microvessels, whose maturation is advanced on POD 14 with gradual diminution of HIF-1alpha. We conclude that (1) transplanted islets strongly express HIF-1alpha in association with beta-cell death and decreased insulin production until adequate revascularization is established and (2) early suppression of HIF-1alpha results in less beta-cell death thereby minimizing early graft failure.

Neuroprotective effect of hyperbaric oxygen in a rat model of subarachnoid hemorrhage.

Acute brain ischemia after subarachnoid hemorrhage (SAH) induces oxidative stress in brain tissues. Up-regulated NADPH oxidase (NOX), a major enzymatic source of superoxide anion in the brain, may contribute to early brain injury after SAH. We evaluated the effects of hyperbaric oxygen (HBO) on protein expression of gp91(phox) catalytic subunit of NOX, lipid peroxidation as a marker of oxidative stress, and on neurological and neuropathological outcomes after SAH. Twenty-nine male Sprague-Dawley rats (300 to 350 g) were randomly allocated to control (sham operation), SAH (endovascular perforation), and SAH treated with HBO groups (2.8 ATA for 2 hours, at 1 hour after SAH). Cerebral blood flow was measured using laser Doppler flowmetry. Rats were sacrificed after 24 hours and brain tissues collected for histology (Nissl staining and gp91 (phox) immunohistochemistry) and biochemistry. Mortality and neurological scores were evaluated. Neuronal injury associated with enhanced gp91 (phox) immunostaining was observed in the cerebral cortex after SAH. The lipid peroxidation product, malondialdehyde, accumulated in the ipsilateral cerebral cortex. HBO treatment reduced expression of NOX, diminished lipid peroxidation, and reduced neuronal damage. HBO caused a drop in mortality and ameliorated functional deficits. HBO-induced neuroprotection after SAH may involve down-regulation of NOX and a subsequent reduction in oxidative stress.

Effect of coenzyme Q(10) on biochemical and morphological changes in experimental ischemia in the rat brain.

The aim of the work was to evaluate an influence of CoQ(10) on lactate acidosis, adenosine-5'-triphosphate (ATP) concentrations, oxidized to reduced glutathione ratio and on superoxide dismutase activity in endothelin model of cerebral ischemia in the rat. Light microscopic studies in the central nervous system and morphometric analysis of pyramidal cells in the hippocampus were also performed. Endothelins (ET-1 or ET-3; 20 pmoles) were injected into the right lateral cerebral ventricle (intracerebroventricularly). CoQ(10) was given intraperitoneally (i.p.) just before the operation (i.p. 10 mgkg b. wt.). More severe changes of investigated biochemical parameters were observed in the animals treated with ET-1 in comparison with ET-3. Recovery was noted earlier in the group subjected to ET-3 and CoQ(10) administration, than in the animals subjected to ET-1 and CoQ(10) treatment. Histopathological observations showed sparse foci of a neuronal loss in the cerebral cortex and in the hippocampus only in the ET-1 model of ischemia. Additionally more numerous dark neurons were present in above brain structures following ET-1 administration comparing with ET-3 one. Morphometrical studies demonstrated that CoQ(10) diminished neuronal injury in the hippocampal CA1, CA2 and CA3 zones. Above data indicate on neuroprotective effect of CoQ(10) as a potent antioxidant and oxygen derived free radicals scavenger in the cerebral ischemia.

The experimental squalene encephaloneuropathy in the rat.

Accumulation of squalene in the CNS is observed after administration of tellurium and squalene has been proposed to be a mediator of tellurium encephaloneuropathy. The aim of this study was to investigate the effects of squalene on the central and peripheral nervous systems in rat at the ultrastructural level. Squalene was administered at a dose of 20 g/kg body weight, once daily for 4 days, and the animals were sacrificed 7 days and 30 days after the initiation of the experiment. After 7 days a mild swelling of mitochondria and dilation of the Golgi complex cisterns in few neurons in the cerebral cortex and hippocampus were observed. The swelling of astrocytes and their processes was also seen. Some myelin sheaths in the cerebral white matter were disintegrated. In the peripheral nervous system (the sciatic nerve), a damage of the Schwann cells, a destruction of the myelin sheaths, and lipid-like deposits between myelin lamellae causing a secondary compression of axons were present. Squalene administration caused a stimulation of fibroblast to synthesize collagen and an activation of macrophages in the perineurium. After 30 days, the lipid-like material was present in some neurons as well as in the myelin sheaths in the central nervous system. Endothelial cells were hypertrophic and a few demonstrated features of apoptosis. Endothelial cell hypertrophy caused a narrowing of vessel lumen associated with an aggregation of blood morphological elements. Disturbances in myelination and swelling of astrocytic processes persisted in the central nervous system. In the peripheral nervous system, lipid-like deposits were localized in some fibroblasts and extracellularly between the collagen fibers in the perineurium. In conclusion, our electron microscopic studies indicate that squalene produces characteristic pathological changes both in the central and peripheral nervous systems. However, these alterations differ in some aspects (changes in endothelia, accumulation of lipid-like material) from the known features of tellurium encephaloneuropathy.

Effect of coenzyme Q10 (CoQ10) on superoxide dismutase activity in ET-1 and ET-3 experimental models of cerebral ischemia in the rat.

The aim of the work was to evaluate the influence of CoQ10 on superoxide dismutase (SOD) activity levels in the rat model of cerebral ischemia induced by endothelins (ET-1 or ET-3). ETs (20 pmol) were injected into the right lateral cerebral ventricle and immediately CoQ10 was given intraperitoneally (10 mg/kg b.w.). In the brains of experimental animals subjected both to ET-1 and ET-2 administration there was observed a decrease of SOD activity in the brain stem, in the cerebrallum and in the cerebral cortex at all time intervals. ET-1, as compared to ET-3 evoked longer lasting disturbances in SOD activity. In the cerebellum and in the cerebral cortex positive effect of CoQ10 and recovery to the control values was noted after 4 hours in the group subjected to ET-3 injection and after 24 hours in the ET-1 treated animal. Investigated brain areas showed different sensitivity to ETs. Above data may indicate on beneficial effect CoQ10 in the cerebral ischemia via decrease of free radicals concentration.

Evaluation of morphological changes after treatment with coenzyme Q10 (CoQ10) in endothelin-1 induced experimental ischemia in the rat.

The aim of the work was to evaluate the effect of CoQ10 (10 mg/kg body weight) on the morphological changes in the rat brain after the Et-1 induced cerebral ischemia. Selective necrotic foci and dark neurons were observed in the cerebral cortex, hippocampal CA1, CA2 sectors and dentate gyrus after the administration of Et-1. Around the necrotic foci, glycogen was deposited 24 hours after the ischemic hypoxia. It seems that histopathological changes evoked by Et-1 indicate the complicated mechanism connected with ischemia. After treatment with CoQ10 only sparse neuronal changes were observed. CoQ10, known oxygen-derived free radicals scavenger diminished neuronal damage in the cerebral cortex and in the hippocampus.

[Effect of hypothermia on lactate acidosis in experimental ischemia of rat brain]. / Wplyw hipotermii na kwasice mleczanowa w doswiadczalnym niedotlenieniu niedokrwiennym w nastepstwie zatoru powietrznego mózgu szczura (doniesienie wstepne).

The aim of the work was to evaluate the effect of hypothermia on lactate level in the rat cerebral ischaemia. Adult male Wistar rats were subjected to injection of 0.05 ml of air into the ligation of left common carotid artery. Lactate level increased in cerebral hemispheres after 4 hours following air emboli. Mild hypothermia (28 degrees-31 degrees C) continued for 4 hours of cerebral ischaemia, and its beneficial effect was observed. A statistically significant decrease of lactate concentration was noted. The above phenomenon was confirmed by the increase of cerebral acidosis after 24 hours when mild hypothermia was interrupted from the 4th hour of the experiment on. It seems to be of a great importance to adjust proper time of initiation and a duration of hypothermia in cerebral ischaemia treatment.

[The effect of coenzyme Q10 on lactate acidosis at the beginning of experimental cerebral ischemia in rats after the use of endothelin 1 (preliminary results)]. / Wplyw koenzymu Q10 na poziom mleczanu w nastepstwie doswiadczalnego niedotlenienia niedokrwiennego mózgu szczura po podaniu endoteliny-1 (doniesienie wstepne).

The aim of the work was to evaluate effect of CoQ10 on the lactate level in the rat brain after administration of Et-1. Fifty-three male Wistar rats (approximately 220-250 g) were used in the experiment. The animals were divided into four groups. 1. control; 2-4 under chloride hydrate anaesthesia, the rats were subjected to stereotaxic injection into right cerebral lateral ventricle: 2. 1 microliter Ringer's solution (control) and i.p. 0.5 ml of soybean oil, 3. 10 pmoles Et-1 diluted in 1 microliter Ringer's solution and i.p. 0.5 ml soybean oil, 4. 10 pmoles Et-1 diluted in 1 microliter Ringer's solution and i.p. 10 mg/kg of the body weight CoQ1O (Sigma). Right and left hemispheres were taken after one hour, 4 and 24 hours and the lactate level was assayed by an enzymatic method. Et-1 evoked a significant increase of lactate level at all experimental time intervals. CoQ10 reduced lactate acidosis after 24 hours from the administration of Et-1. The above phenomenon can be explained among other by an improvement of the cellular respiratory activity. CoQ10 represents very important electron transporter from flavins to cytochromes in the respiratory chain. Therefore CoQ10 can be used for prevention and treatment of ischaemic insult in human cases.

Experimental squalene encephaloneuropathy in the rat.

To investigate the influence of squalene on the nervous system, adult male Wistar rats were injected with squalene subcutaneously with 20 g/kg of the body weight for 4 consecutive days. After 7 or 30 days from the initiation of the experiment, brain and ischiadic nerves were harvested for electron microscopy. Squalene affected mostly PNS targeting Schwann cells and myelin sheaths. Accumulation of lipid-like droplets in the myelin sheaths in the PNS and in the neurons in the brain cortex, hypertrophy of endothelium, and sometimes endothelial apoptosis in blood vessels, and increased synthesis of collagen in the ischiadic nerve were characteristic for developed squalene encephaloneuropathy.