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Transient Cerebral Ischemia (transient + cerebral_ischemia)
Selected AbstractsDoes rat global transient cerebral ischemia serve as an appropriate model to study emotional disturbances?FUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 6 2004Guy Bernard Bantsiele Abstract We used two validated psychopharmacological methods, the forced swimming test (FST 20 min and 5 min) and the elevated plus-maze (EPM), to quantify depression-like and anxiety-like behavior induced by transient global cerebral ischemia in the rat. We also validated use of these methods for the study of antidepressant (imipramine) and anti-anxiety drugs (diazepam). Twelve days after surgery to provoke transient global ischemia, spontaneous motor activity was 40% higher in ischemic rats than in sham-operated controls. Duration of immobility during the FST 20 min and 5 min was 28 and 30% shorter, respectively, than in controls. Treatment with imipramine (3 × 30 mg/kg i.p.) induced a significantly shorter duration of immobility during the FST 5 min, but with no difference between ischemia and control rats. The EPM demonstrated that ischemia did not induce any change in the six behavior parameters measured. Diazepam (1.5 mg/kg i.p.) induced significant anxiolytic effects which were similar in ischemic and sham-operated animals. Both tests failed to demonstrate perturbed performance but conversely, these findings did disclose the sensitivity of ischemia-exposed rats to the action of imipramine and diazepam, demonstrating the usefulness of these tests as psychopharmocological tools for evaluating the effect of psychotropics in the ischemic rat. [source] Citicoline: neuroprotective mechanisms in cerebral ischemiaJOURNAL OF NEUROCHEMISTRY, Issue 1 2002Rao Muralikrishna Adibhatla Abstract Cytidine-5,-diphosphocholine (citicoline or CDP-choline), an intermediate in the biosynthesis of phosphatidylcholine (PtdCho), has shown beneficial effects in a number of CNS injury models and pathological conditions of the brain. Citicoline improved the outcome in several phase-III clinical trials of stroke, but provided inconclusive results in recent clinical trials. The therapeutic action of citicoline is thought to be caused by stimulation of PtdCho synthesis in the injured brain, although the experimental evidence for this is limited. This review attempts to shed some light on the properties of,citicoline that are responsible for its effectiveness. Our studies in transient cerebral ischemia suggest that citicoline might enhance reconstruction (synthesis) of PtdCho and sphingomyelin, but could act by inhibiting the destructive processes (activation of phospholipases). Citicoline neuroprotection may,include: (i) preserving cardiolipin (an exclusive inner mitochondrial membrane component) and sphingomyelin; (ii),preserving the arachidonic acid content of PtdCho and phosphatidylethanolamine; (iii) partially restoring PtdCho levels; (iv) stimulating glutathione synthesis and glutathione reductase activity; (v) attenuating lipid peroxidation; and (vi),restoring Na+/K+ -ATPase activity. These observed effects,of citicoline could be explained by the attenuation of,phospholipase A2 activation. Based on these findings, a singular unifying,mechanism has been hypothesized. Citicoline also provides choline for synthesis of neurotransmitter acetylcholine, stimulation of tyrosine hydroxylase activity and dopamine release. [source] Diazepam Promotes ATP Recovery and Prevents Cytochrome c Release in Hippocampal Slices After In Vitro IschemiaJOURNAL OF NEUROCHEMISTRY, Issue 3 2000Francesca Galeffi Abstract: Benzodiazepines protect hippocampal neurons when administered within the first few hours after transient cerebral ischemia. Here, we examined the ability of diazepam to prevent early signals of cell injury (before cell death) after in vitro ischemia. Ischemia in vitro or in vivo causes a rapid depletion of ATP and the generation of cell death signals, such as the release of cytochrome c from mitochondria. Hippocampal slices from adult rats were subjected to 7 min of oxygen-glucose deprivation (OGD) and assessed histologically 3 h after reoxygenation. At this time, area CA1 neurons appeared viable, although slight abnormalities in structure were evident. Immediately following OGD, ATP levels in hippocampus were decreased by 70%, and they recovered partially over the next 3 h of reoxygenation. When diazepam was included in the reoxygenation buffer, ATP levels recovered completely by 3 h after OGD. The effects of diazepam were blocked by picrotoxin, indicating that the protection was mediated by an influx of Cl - through the GABAA receptor. It is interesting that the benzodiazepine antagonist flumazenil did not prevent the action of diazepam, as has been shown in other studies using the hippocampus. Two hours after OGD, the partial recovery of ATP levels occurred simultaneously with an increase of cytochrome c (,400%) in the cytosol. When diazepam was included in the reoxygenation buffer, it completely prevented the increase in cytosolic cytochrome c. Thus, complete recovery of ATP and prevention of cytochrome c release from mitochondria can be achieved when diazepam is given after the loss of ATP induced by OGD. [source] Hypothyroid state does not protect but delays neuronal death in the hippocampal CA1 region following transient cerebral ischemia: Focus on oxidative stress and gliosisJOURNAL OF NEUROSCIENCE RESEARCH, Issue 12 2010Choong Hyun Lee Abstract We investigated protective effects of hypothyroidism on delayed neuronal death, gliosis, lipid peroxidation and Cu,Zn-superoxide dismutase (SOD1) in the gerbil hippocampal CA1 region (CA1) after 5 min of transient cerebral ischemia. The hypothyroidism was induced by 0.025% methimazole treatment. Free triiodothyronine and thyroxine levels were markedly decreased in the hypothyroid group. Four days after ischemia/reperfusion, only a few NeuN-immunoreactive (+) neurons were detected in the CA1 of euthyroid-ischemia (eu-ischemia) group; however, at this time point, the number of NeuN+ neurons was significantly higher in the hypothyroid-ischemia (hypo-ischemia) group than in the eu-ischemia group. At 5 days postischemia, NeuN+ neurons were significantly decreased in the hypo-ischemia group: The number of NeuN+ neurons in this group was similar to that in the eu-ischemia group. Activations of GFAP+ astrocytes and Iba-1+ microglia in the CA1 were higher in the eu-ischemia group 3 and 4 days after ischemia/reperfusion. At 5 days postischemia, the activations of both the glial cells in the CA1 were similar between the two groups. 4-Hydroxy-2-nonenal (HNE), a marker for lipid peroxidation, immunoreactivity in the eu-ischemia group was higher than in the hypo-ischemia group; at 5 days postischemia, the immunoreactivity was similar between the two groups. In contrast, SOD1 level was lower in the CA1 of the eu-ischemia group. These results suggest that hypothyroid state does not protect against delayed neuronal death but only delays the neuronal death in the hippocampal CA1 region after transient cerebral ischemia by reducing lipid peroxidation and increasing SOD1. © 2010 Wiley-Liss, Inc. [source] Role of vascular endothelial growth factor in neuronal DNA damage and repair in rat brain following a transient cerebral ischemiaJOURNAL OF NEUROSCIENCE RESEARCH, Issue 2 2002Zeng-Jin Yang Abstract The antisense knockdown technique and confocal laser scanning microscopic analysis were used to elucidate vascular endothelial growth factor (VEGF) induction and its effect on DNA damage and repair in rat brain following a transient middle cerebral artery occlusion. Immunohistochemical study and in situ hybridization showed that the expression of VEGF and its mRNA was enhanced in the ischemic core and penumbra of ischemic brain. Western blot analysis further illustrated that VEGF induction was time-dependently changed in these areas. Double-staining analysis indicated that VEGF-positive staining existed in the neuron, but not in the glia, and it colocalized with excision repair cross-complementing group 6 (ERCC6) mRNA, a DNA repair factor. VEGF antisense oligodeoxynucleotide infusion reduced VEGF induction and resulted in an enlargement of infarct volume of the brain caused by ischemia. Moreover, it also increased the number of DNA damaged cells and lessened the induction of ERCC6 mRNA in ischemic brains. These results suggest that the induction of endogenous VEGF in ischemic neurons plays a neuroprotective role probably associated with the expression of ERCC6 mRNA. © 2002 Wiley-Liss, Inc. [source] Protective effects of melatonin in ischemic brain injuryJOURNAL OF PINEAL RESEARCH, Issue 4 2000Salvatore Cuzzocrea Recent studies have demonstrated that melatonin is a scavenger of oxyradicals and peroxynitrite and an inhibitor of nitric oxide (NO) production. NO, peroxynitrite (formed from NO and superoxide anion), and poly (ADP-Ribose) synthetase (PARS) have been implicated as mediators of neuronal damage following focal ischemia. In the present study, we have investigated the effects of melatonin treatment in Mongolian gerbils subjected to cerebral ischemia. Treatment of gerbils with melatonin (10 mg kg,1, 30 min before reperfusion and 1, 2, and 6 hr after reperfusion) reduced the formation of post-ischemic brain edema, evaluated by water content. Melatonin also attenuated the increase in the brain levels malondialdehyde (MDA) and the increase in the hippocampus of myeloperoxidase (MPO) caused by cerebral ischemia. Positive staining for nitrotyrosine was found in the hippocampus of Mongolian gerbils subjected to cerebral ischemia. Hippocampus tissue sections, from Mongolian gerbils subjected to cerebral ischemia, also showed positive staining for PARS. The degrees of staining for nitrotyrosine and for PARS were markedly reduced in tissue sections obtained from animals that received melatonin. Melatonin treatment increased survival and reduced hyperactivity linked to neurodegeneration induced by cerebral ischemia and reperfusion. Histological observations of the pyramidal layer of CA-1 showed a reduction of neuronal loss in animals that received melatonin. These results show that melatonin improves brain injury induced by transient cerebral ischemia. [source] Vascular endothelial growth factor gene expression in middle cerebral artery occlusion in the ratACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2005F. Lennmyr Background:, Focal cerebral ischemia induces up-regulation of angiogenic growth factors such as vascular endothelial growth factor (VEGF), which may have both beneficial and harmful effects to the ischemic brain. Vascular endothelial growth factor is up-regulated in models of brain ischemia, but the underlying mechanisms in vivo remain unclear. In the present report we have investigated the concomitant changes in VEGF and glyceraldehyde dehydrogenase (GAPDH) mRNA expression in a model of permanent and transient cerebral ischemia. Methods:, Male Sprague-Dawley rats were exposed to permanent or transient (2 h) middle cerebral artery occlusion (PMCAO, TMCAO). Brain samples were collected at survival times ranging from 6 h to 1 week, and the levels of VEGF164 and GAPDH mRNA were determined using reverse-transcriptase real-time polymerase chain reaction (RT-PCR). Results:, The VEGF mRNA levels decreased gradually over the observation period in a similar manner in both PMCAO and TMCAO. Maximum levels, seen at early observation time points, did not significantly deviate from sham controls. No statistically significant changes in GAPDH mRNA levels were observed, but there was a tendency towards a postischemic decrease with subsequent return to control levels over time. The VEGF/GAPDH ratio followed a pattern of decrease similar to VEGF mRNA alone. Conclusion:, The VEGF mRNA levels at 6 h after MCAO remain near baseline and thereafter decline, regardless of whether the occlusion is permanent or transient (2 h). The findings raise the question of other than transcriptional regulation of VEGF in cerebral ischemia. [source] | |||||||||||||