Global Cerebral Ischemia-reperfusion Research Articles

The Protective Effect of Remote Renal Preconditioning Against Hippocampal Ischemia Reperfusion Injury: Role of KATP Channels.

Remote ischemic preconditioning (RIPC), which consists of several brief ischemia/reperfusion applied at the remote site of lethal ischemia reperfusion, can, through activating different mechanisms, increase the ability of the body's endogenous protection against prolonged ischemia/reperfusion. Recent studies have shown that RIPC has neuroprotective effects, but its mechanisms are not well elucidated. The present study aimed to determine whether activation of KATP channels in remote renal preconditioning decreases hippocampus damage induced by global cerebral ischemia. RIPC was induced by ischemia of the left renal artery (IPC); 24 h later, global cerebral ischemia reperfusion (IR) was induced by common carotid arteries occlusion. 5hydroxydecanoate (5HD) and glibenclamide (Gli) were injected before of IPC. The levels of malondialdehyde (MDA) and catalase (CAT) activity were assessed in hippocampus. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) was assessed to detect apoptotic cells in hippocampus. RIPC inhibited apoptosis by decreasing positive TUNEL cells (P < 0.05). KATP channels blocking with 5HD and Gli markedly increased apoptosis in hippocampal cells in RIPC group (P < 0.001). RIPC decreased MDA level and increased CAT activity in ischemic hippocampus (P < 0.01). Also, 5HD and Gli inhibited the effect of RIPC on MDA level and CAT activity (P < 0.05). The present study shows that RIPC can effectively attenuate programmed cell death, increase activity of CAT, and reduce MDA levels. Blocking of KATP channels inhibited the protective effects of RIPC.

Short-term sleep deprivation stimulates hippocampal neurogenesis in rats following global cerebral ischemia/reperfusion.

BackgroundSleep deprivation (SD) plays a complex role in central nervous system (CNS) diseases. Recent studies indicate that short-term SD can affect the extent of ischemic damage. The aim of this study was to investigate whether short-term SD could stimulate hippocampal neurogenesis in a rat model of global cerebral ischemia/reperfusion (GCIR).MethodsOne hundred Sprague-Dawley rats were randomly divided into Sham, GCIR and short-term SD groups based on different durations of SD; the short-term SD group was randomly divided into three subgroups: the GCIR+6hSD*3d-treated, GCIR+12hSD-treated and GCIR+12hSD*3d-treated groups. The GCIR rat model was induced via the bilateral occlusion of the common carotid arteries and hemorrhagic hypotension. The rats were sleep-deprived starting at 48 h following GCIR. A Morris water maze test was used to assess learning and memory ability; cell proliferation and differentiation were analyzed via 5-bromodeoxyuridine (BrdU) and neuron-specific enolase (NSE), respectively, at 14 and 28 d; the expression of hippocampal BDNF was measured after 7 d.ResultsThe different durations of short-term SD designed in our experiment exhibited improvement in cognitive function as well as increased hippocampal BDNF expression. Additionally, the short-term SD groups also showed an increased number of BrdU- and BrdU/NSE-positive cells compared with the GCIR group. Of the three short-term SD groups, the GCIR+12hSD*3d-treated group experienced the most substantial beneficial effects.ConclusionsShort-term SD, especially the GCIR+12hSD*3d-treated method, stimulates neurogenesis in the hippocampal dentate gyrus (DG) of rats that undergo GCIR, and BDNF may be an underlying mechanism in this process.

The protective effect of caffeic acid on global cerebral ischemia-reperfusion injury in rats.

Ischemic stroke is a major cause of death and disability all over the world. Ischemic stroke results from a temporary or permanent reduction of cerebral blood flow that leads to functional and structural damage in different brain regions. Despite decades of intense research, the beneficial treatment of stroke remains limited. In light of this, the search for effective means ameliorating cerebral ischemia-reperfusion injury (CIRI) is one of the major problems of experimental medicine and biology. Recently, the 5-Lipoxygenase (5-LO, a key enzyme metabolizing arachidonic acid to produce leukotrienes) inhibitors have been showed to protect brain against ischemic damage in animal model of cerebral ischemia. Caffeic acid, an inhibitor of 5-LO, is a phenolic compound widely distributed in medicinal plants. The aim of this study was to investigate the effect of caffeic acid on global cerebral ischemia-reperfusion injury in rats. The study was carried out on 45 rats that were randomly divided into five groups: the sham group (n = 9), I/R non-treated group (n = 9), I/R-caffeic acid group (10 mg · kg−1) (n = 9), I/R-caffeic acid group (30 mg · kg−1) (n = 9) and I/R-caffeic acid group (50 mg · kg−1) (n = 9). Global cerebral ischemia was induced by bilateral carotid artery occlusion for 20 min followed by reperfusion. Spatial learning and memory was evaluated using Morris water maze. Histopathological changes of hippocampus neurons was observed using HE staining. Superoxide dismutase (SOD, the antioxidant enzyme) activities and malondialdehyde (MDA, an oxidative stress biomarker) contents were detected. NF-κBp65 expression was detected by the methods of immunohistochemistry. Caffeic acid markedly reduced the escape latency, relieved hippocampal neurons injury and increased neuron count compared with those of I/R non-treated rat. NF-κBp65 expression and MDA content decreased significantly, and SOD activities increased significantly in hippocampus. Compared with sham group, 5-LO expression increase significantly in I/R non-treated group rat, and caffeic acid markedly reduced 5-LO expression. The results of the study suggest that caffeic acid has a significant protective effect on global cerebral ischemia-reperfusion injury in rats. The neuroprotective effects is likely to be mediated through the inhibition of 5-LO.

The Yin and Yan of Adenosine A1 and A2A Receptors in Global Cerebral Ischemia Reperfusion Injury

Global cerebral ischemia reperfusion (IR) following cardiac arrest, shock and asphyxia can affect wide brain areas where new therapies are imperative. Moreover, many intracellular pathways mediating tissue response to IR are still elusive. Adenosine is a neuromodulator that greatly impacts IR through the inhibitory A1 and excitatory A2 receptors. Studies indicate that both adenosine A1 agonists and A2A antagonists are neuroprotective during ischemic insults. However, many of the signaling pathways affecting such responses are largely unknown. In the current study, bilateral carotid occlusion for 45 min. followed by 24h reperfusion period resulted in histopathological damage as well as memory impairment, motor incoordination and increased locomotor activity. Such events were attenuated by unilateral intra‐hippocampal injection of both the selective A1 agonist N6‐cyclohexyl adenosine (CHA) and the A2A antagonist 7‐(2‐phenylethyl)‐5‐amino‐2‐(2‐furyl)‐pyrazolo‐[4,3‐e]‐1,2,4‐triazolo[1,5‐c]pyrimidine (SCH58261). On the cellular level, IR increased glutamate, pERK1/2, c‐Fos, NF‐kB, TNF‐α, cytochrome c, caspase‐3, BDNF, Nrf2 and IL‐10 contents. Both CHA and SCH58261signifiantly reduced glutamate, c‐Fos, TNF‐α, cytochrome c, caspase‐3 and increased Nrf‐2 and IL‐10 contents. While only SCH58261 reduced pERK1/2, NF‐kB and BDNF contents. By the same token, iNOS and TBARS levels were increased following IR and attenuated by both CHA and SCH58261 treatments. Accordingly, these results lend insight to the neuroprotective effects of A1 and A2A agonists and antagonists respectively where pERK1/2 and NF‐kB pathways might be involved in adenosine mediated attenuation of inflammation, apoptosis and oxidative stress.

Effect of dexmedetomidine on oxidative stress responses during global cerebral ischemia-reperfusion in rats

Objective To evaluate the effects of dexmedetomidine on the oxidative stress responses during global cerebral ischemia-reperfusion (I/R) in rats. Methods Thirty-six male Sprague-Dawley rats, weighing 250-300 g, were randomly divided into 3 groups (n=12 each) using a random number table: sham operation group (group S), global cerebral I/R group (group I/R) and dexmedetomidine group (group D). Global cerebral ischemia was induced by occlusion of bilateral common carotid arteries combined with hypotension (MAP maintained at 35-45 mmHg). In group D, dexmedetomidine was infused at a rate of 3 μg·kg-1·h-1until 2 h of reperfusion after a loading dose of dexmedetomidine 3 μg/kg was intravenously injected immediately after onset of reperfusion.The neurological deficit score (NDS) was assessed at 24 h of reperfusion, the rats were then sacrificed, and their brains were immediately removed for determination of cell apoptosis and levels of malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT). Apoptotic rate was calculated. Results Compared with group S, NDS, apoptotic rate and MDA level were significantly increased, and SOD and CAT levels were decreased in I/R and D groups.Compared with group I/R, NDS, apoptotic rate and MDA level were significantly decreased, and SOD and CAT levels were increased in group D. Conclusion Dexmedetomidine attenuates global cerebral I/R injury through inhibiting the oxidative stress responses. Key words: Dexmedetomidine; Reperfusion injury; Brain; Oxidative stress

Ischemic preconditioning and postconditioning alleviates hippocampal tissue damage through abrogation of apoptosis modulated by oxidative stress and inflammation during transient global cerebral ischemia–reperfusion in rats

Introduction: It has been argued recently that ischemic preconditioning (IPre) and postconditioning (IPost) have beneficial effects in many ischemic disorders however; their effects on global ischemia/reperfusion (I/R) are poorly understood. Thus, the present work aimed to study the possible mechanisms underlying the neuroprotective effects of IPre and IPost.Methods: Animals were randomly allocated into 4 groups (n=30): (1) Sham operated (SO); (2) I/R group, animals were subjected to 15min global ischemia followed by 60min reperfusion; (3) IPre, animals were subjected to 3 episodes of 5min ischemia followed by 10min reperfusion before I/R; (4) IPost, animals were subjected to three episodes of 10s of ischemia and 10s of reperfusion after the period of ischemia followed by a 60min reperfusion period. Lactate dehydrogenase activity, oxidative stress, inflammatory and apoptotic biomarkers, as well as neurotransmitters, infarct size and histopathological examination were assessed.Results: I/R induced hippocampal damage through increasing oxidative stress, inflammatory, excitotoxic and apoptotic markers as well as lactate dehydrogenase activity and infarct size. Both, IPre and IPost attenuated most markers induced by I/R.Conclusions: IPre and IPost neuroprotective effects can be explained through their anti-oxidant, anti-inflammatory and anti-apoptotic mechanisms.

Role of PI3K/Akt signaling pathway in mild head hypothermia-induced reduction of global cerebral ischemia-reperfusion injury in rats

Objective To evaluate the role of phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway in mild head hypothermia-induced reduction of global cerebral ischemia-reperfusion (I/R) injury in rats. Methods Sixty male Sprague-Dawley rats, weighing 250-280 g, were randomly divided into 5 groups (n=12 each) using a random number table: sham operation group (group S), group I/R, mild hypothermia + I/R group (group H), mild hypothermia + I/R + solvent control group (group DM), and mild hypothermia + I/R + PI3K inhibitor LY294002 group (group LY). Global cerebral I/R was induced by modified four-vessel occlusion method described by Pulsinelli. In H group, when the hippocampal temperature was decreased to 33℃ using nasopharyngeal cooling, the bilateral common carotid arteries were occluded for 15 min followed by reperfusion, and hippocampal hypothermia was maintained at 32.5-33.5 ℃ for 1 h. In DM and LY groups, DMSO and LY294002 5 μl were injected into the left ventricle, respectively, and 20 min later the other procedures were similar to those previously described in group H. At 8 h of reperfusion, 6 rats were sacrificed, and hippocampal specimens were obtained to detect the expression of pFoxO3a, Bcl-2 and Bax (by immuno-histochemistry). The expression of phosphor-Akt (p-Akt) was determined by Western blot. Results Compared with group S, the expression of p-Akt, pFoxO3a and Bcl-2 was significantly up-regulated in I/R, H and DM groups, the expression of Bcl-2 was down-regulated, and the ratio of Bcl-2/Bax was increased in H and DM groups, and the ratio of Bcl-2/Bax was decreased in I/R and LY groups. Compared with group I/R, the expression of p-Akt, pFoxO3a and Bcl-2 was significantly up-regulated, the expression of Bcl-2 was down-regulated, and the ratio of Bcl-2/Bax was increased in H and DM groups. Compared with H and DM groups, the expression of p-Akt, pFoxO3a and Bcl-2 was down-regulated, the expression of Bax was up-regulated, and the ratio of Bcl-2/Bax was decreased in group LY. Conclusion PI3K/Akt signaling pathway is involved in reduction of global cerebral I/R injury by mild head hypothermia in rats. Key words: Phosphoinositide-3-kinase; Protein-serine-threonine kinases; Hypothermia, induced; Reperfusion injury; Brain

Neuroprotection, learning and memory improvement of a standardized extract from Renshen Shouwu against neuronal injury and vascular dementia in rats with brain ischemia

Ethnopharmacological relevanceThe Renshen Shouwu capsule (RSSW) is a patented Traditional Chinese Medicine (TCM), that has been proven to improve memory and is widely used in China to apoplexy syndrome and memory deficits. To investigate the neuroprotective and therapeutic effect of the Renshen Shouwu standardized extract (RSSW) on ischemic brain neuronal injury and impairment of learning and memory related to Vascular Dementia (VD) induced by a focal and global cerebral ischemia-reperfusion injury in rats. Material and methodsUsing in vivo rat models of both focal ischemia/reperfusion (I/R) injuries induced by a middle cerebral artery occlusion (MCAO), and VD with transient global brain I/R neuronal injuries induced by a four-vessel occlusion (4-VO) in Sprague–Dawley (SD) rats, RSSW (50,100, and 200mgkg−1 body weights) and Egb761® (80mgkg−1) were administered orally for 20 days (preventively 6 days+therapeutically 14 days) in 4-VO rats, and for 7 days (3 days preventively+4 days therapeutically) in MCAO rats. Learning and memory behavioral performance was assayed using a Morris water maze test including a place navigation trial and a spatial probe trial. Brain histochemical morphology and hippocampal neuron survival was quantified using microscope assay of a puffin brain/hippocampus slice with cresyl violet staining. ResultsMCAO ischemia/reperfusion caused infarct damage in rat brain tissue. 4-VO ischemia/reperfusion caused a hippocampal neuronal lesion and learning and memory deficits in rats. Administration of RSSW (50, 100, and 200mg/kg) or EGb761 significantly reduced the size of the insulted brain hemisphere lesion and improved the neurological behavior of MCAO rats. In addition, RSSW markedly reduced an increase in the brain infarct volume from an I/R-induced MCAO and reduced the cerebral water content in a dose-dependent way. Administration of RSSW also increased the pyramidal neuronal density in the hippocampus of surviving rats after transient global brain ischemia and improved the learning and memory ability of rats with 4-VO induced vascular dementia in a dose-dependent manner. ConclusionsThe in vivo results suggested that RSSW has significant neuroprotective effects against MCAO and 4-VO I/R injury and a therapeutic effect on cognitive disorders in VD rats. RSSW also improved the learning and memory ability of VD rats. These results convincingly demonstrated that RSSW may be useful to prevent and treat ischemia/reperfusion injury and vascular dementia disease.

Role of FOXO3a in process of hydrogen-rich saline attenuating global cerebral ischemia-reperfusion injury in rats

To investigate the role of FOXO3a in process of hydrogen-rich saline attenuating global cerebral ischemia-reperfusion (I/R) injury in rats. Seventy-two male Sprague Dawley rats, weighing 280-320 g, were randomly divided into six groups (n = 12 each) : sham operation group (group I), cerebral ischemia-reperfusion group (group II), hydrogen-rich saline group (group III), vehicle group (group IV), JNK inhibitor SP600125 group (group V), JNK inhibitor+hydrogen-rich saline group (group VI). Global cerebral I/R was produced by transesophageal pacing inducing cardiac arrest (CA) method. Cardiopulmonary resuscitation (CPR) and mechanical ventilation was implemented at the end of 4 min for CA. In groups III and VI, hydrogen-rich saline 5 ml/kg was intraperitoneally immediately and 6 hours after reperfusion, while equel volume of nomal saline was injected in the other four groups. The rats in groups V and VI received intracerebroventricular injection of JNK inhibitor SP600125 10 µl 30 min before ischemia, while group IV received intracerebroventricular injection of equal volume of DMSO. Neuro Deficit Score (NDS) was evaluated at 24 h of reperfusion. Then rats were sacrificed, and the global brain tissues were obtained and stained with HE for examination of the changes in pyramidal cells in the CA1 region of hippocampus. The bilateral hippocampi were romoved for detection of the expression of p-JNK, JNK and FOXO3a using Western Blotting. Compared with group I, the expression of p-JNK, nuclear FOXO3a and the level of NDS were significantly up-regulated, and the number of pyramidal cells and was decreased in group II and IV. Compared with group II, the expression of p-JNK, nuclear FOXO3a and the level of NDS were significantly down-regulated, and the number of pyramidal cells was increased in group III, V and VI. Hydrogen-rich saline can attenuate global cerebral I/R injure through inhibiting JNK, reducing the expression of FOXO3a.

Effect of Cyperus rotundus on ischemia-induced brain damage and memory dysfunction in rats.

Global cerebral ischemia-reperfusion injury causes loss of pyramidal cells in CA1 region of hippocampus. In this study, we investigated the possible neuroprotective effects of the ethanol extract of Cyperus rotundus (EECR) on a model of global transient ischemia in rat, by evaluating the pathophysiology of the hippocampal tissue and spatial memory. Treatment group (EECR, 100 mg/kg/day) was gavaged from 4 days before, to 3 days after ischemia. Morris water maze test was performed 1 week after ischemia for 4 days. Brain tissue was prepared for Nissl staining. Our data showed no statistical difference between the treatment and ischemia groups in water maze task. So, treatment of ischemia with EECR cannot improve spatial learning and memory. On the contrary EECR ameliorated the CA1 pyramidal cell loss due to transient global ischemia/reperfusion injury. These results suggest that EECR cannot reduce the ischemia-induced, cognitive impairments seen after transient, global cerebral ischemia but can prevent pyramidal cell loss in CA1 region of hippocampus.

Effects of dexmedetomidine combined with mild hypothermia on global cerebral ischemia-reperfusion injury in neonatal rats

Objective To evaluate the effects of combination of dexmedetomidine and mild hypothermia on global cerebral ischemia-reperfusion(I/R)injury in neonatal rats. Methods Ninety-six neonatal Sprague-Dawley rats, aged 6-7 days, weighing 18-22 g, were randomly divided into 4 groups(n=24 each)using a random number table: I/R group, mild hypothermia group(group H), dexmedetomidine group(group D)and combination of dexmedetomidine and mild hypothermia group(group DH). Global cerebral ischemia was induced in rats anaesthetized with chloral hydrate by bilateral common carotid artery clamping(for 15 min)combined with hypotension followed by reperfusion.Dexmedetomidine 75 μg/kg was given intraperitoneally at 30 min before ischemia in D and DH groups, while the equal volume of normal saline was given in I/R and H groups.The temperature in the temporal muscle was maintained at 36.7-37.2℃ in I/R and D groups, and at 34.8-35.3℃ in H and DH groups.At 12, 24 and 72 h of reperfusion, 8 rats were randomly chosen in each group, and neurological deficit score(NDS)was determined.The animals were then sacrificed, and their brains were removed for determination of myeloperoxidase(MPO)activity(by spectrophotometry)and contents of tumor necrosis factor-alpha(TNF-α)and interleukin-6(IL-6)in brain tissues(using ELISA). Results Compared with I/R group, the NDS, MPO activity and contents of TNF-α and IL-6 were significantly decreased in the other three groups.The NDS, MPO activity and contents of TNF-α and IL-6 were significantly lower in DH group than in H or D group. Conclusion Dexmedetomidine can optimize cerebral protection providedby mild hypothermia against global cerebral I/R injury through inhibiting inflammatory responses in brain tissues of neonatal rats. Key words: Dexmedetomidine; Hypothermia, induced; Infant, newborn; Reperfusion injury; Brain

Effects of intermittent hypobaric hypoxia preconditioning on the expression of neuroglobin and Bcl-2 in the rat hippocampal CA1 area following ischemia-reperfusion.

This study was aimed at understanding the effect of intermittent hypobaric hypoxia preconditioning (IHHP) on neuroglobin (NGB) and Bcl-2 expression in the hippocampal CA1 region of rats following global cerebral ischemia-reperfusion. Wistar rats were randomly divided into sham, IHHP control, global cerebral ischemia-reperfusion (IR group), and IHHP+IR groups. The four-vessel occlusion rat model of Pulsinelli was used for the IR groups, in which the common carotid artery was occluded for 8 min before reperfusion. Thionin and immunohistochemical staining were used to observe NGB and Bcl-2 expression in the hippocampal CA1 region. Data was analyzed using the SPSS software. There was a significant increase in the number of surviving cells in the hippocampal CA1 region of the IHHP+IR group (119.5 ± 14) compared to the IR group (41.7 ± 3.8) (P < 0.05). There was a significant increase in the expression of NGB and Bcl-2 in the hippocampal CA1 region of the IHHP+IR group compared to the IR group. By upregulating hippocampal NGB and Bcl-2 expression, IHHP may play a role in neural protection by reducing hippocampal neuronal apoptosis following IR.

Medicinal plants in management of type 2 diabetes and neurodegenerative disorders.

Medicinal plants in management of type 2 diabetes and neurodegenerative disorders.

The Neuroprotective Effects of Resveratrol Preconditioning in Transient Global Cerebral Ischemia-Reperfusion in Mice.

This study was designed to elucidate the neuroprotective effect of resveratrol in a mouse model of bilateral common carotid artery occlusion (BCCAO). Sixty male C57BL/6 mice, weighing 20-24 g, were used in our experiments. The mice were randomly assigned into three groups: control group, BCCAO group and BCCAO+Resveratrol group. Neurological score was assessed 24h, 48h, 72h after BCCAO, respectively. Hematoxylin and eosin (H&E) staining, NeuN and TUNEL were performed to detect the neuronal death and survival. The expression of Bcl-2, Bax, caspase-3, and cleaved caspase-3 were also detected to assess the anti-apoptotic effect of resveratrol by Western Blot. Resveratrol significantly improved neurological score in BCCAO mice. Besides, it attenuates neuronal apoptosis via increasing the expression of Bcl-2 and decreasing the expression of Bax, caspase-3, and cleaved caspase-3. Resveratrol promotes neuronal survival in mice subjected to BCCAO. Resveratrol is beneficial in the model of BCCAO, which is associated with its anti-apoptotic effect.

Tea polyphenols may attenuate the neurocognitive impairment caused by global cerebral ischemia/reperfusion injury via anti-apoptosis

Background/aims: Global cerebral ischemia/reperfusion (GCIR) may incur neurocognitive impairment. Tea polyphenols (TP) have strong anti-oxidant capacity. This study planned to investigate the protective effect of TP against the neurocognitive impairment caused by GCIR and its mechanism.Methods: One-stage anterior approach for cerebral four-vessel occlusion (4VO) was used to construct the GCIR model. Sprague Dawley rats were randomly classified into Sham group, GCIR group, and TP group (n = 50 per group). Besides receiving the same 4VO, the rats in TP group were treated with TP (6.4%) injection from the tail vein 30 minutes before cerebral ischemia. Morris water-maze test was used to evaluate the changes in space recognition and memory and open field activity test to assess the activity and motor function of rats. The cell apoptotic study in hippocampal CA1 region at specified time points (12, 24, 48, and 72 hours after surgery) was carried out by the flow cytometry, histology (hematoxylin and eosin staining), and immunohistochemical (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining) examinations. One-way analysis of variance and least significant difference t-test were used and statistical significance considered at P < 0.05.Results: Compared with the GCIR group, the TP group was significantly attenuated in the impairment of space recognition and memory caused by GCIR and so was the neuronal apoptosis in the hippocampal CA1 region (P < 0.05).Conclusion: TP may attenuate the impairment of space recognition and memory caused by GCIR via anti-apoptosis.

Deciphering of mitochondrial cardiolipin oxidative signaling in cerebral ischemia-reperfusion.

It is believed that biosynthesis of lipid mediators in the central nervous system after cerebral ischemia-reperfusion starts with phospholipid hydrolysis by calcium-dependent phospholipases and is followed by oxygenation of released fatty acids (FAs). Here, we report an alternative pathway whereby cereberal ischemia-reperfusion triggered oxygenation of a mitochondria-specific phospholipid, cardiolipin (CL), is followed by its hydrolysis to yield monolyso-CLs and oxygenated derivatives of fatty (linoleic) acids. We used a model of global cerebral ischemia-reperfusion characterized by 9 minutes of asphyxia leading to asystole followed by cardiopulmonary resuscitation in postnatal day 17 rats. Global ischemia and cardiopulmonary resuscitation resulted in: (1) selective oxidation and hydrolysis of CLs, (2) accumulation of lyso-CLs and oxygenated free FAs, (3) activation of caspase 3/7 in the brain, and (4) motor and cognitive dysfunction. On the basis of these findings, we used a mitochondria targeted nitroxide electron scavenger, which prevented CL oxidation and subsequent hydrolysis, attenuated caspase activation, and improved neurocognitive outcome when administered after cardiac arrest. These data show that calcium-independent CL oxidation and subsequent hydrolysis represent a previously unidentified pathogenic mechanism of brain injury incurred by ischemia-reperfusion and a clinically relevant therapeutic target.

Montelukast, a cysteinyl leukotriene receptor-1 antagonist protects against hippocampal injury induced by transient global cerebral ischemia and reperfusion in rats.

Cysteinyl leukotrienes (CysLTs) are potent pro-inflammatory and immune modulating lipid mediators involved in inflammatory diseases and were boosted in human brain after acute phase of cerebral ischemia. The antagonism of CysLTs receptors may offer protection against ischemic damage. Therefore it seemed interesting to study the possible neuroprotective effect of Montelukast, a CysLTR1 antagonist in global cerebral ischemia/reperfusion (IR) injury in rats. Global cerebral ischemia-reperfusion was induced by bilateral carotid artery occlusion for 15 min followed by 60 min reperfusion period. Animals were randomly allocated into three groups (n = 30 per group): Sham operated, I/R control and rats treated with montelukast (0.5 mg/kg, po) daily for 7 days then I/R was induced 1 h after the last dose of montelukast. After reperfusion rats were killed by decapitation, brains were removed and both hippocampi separated and the following biochemical parameters were estimated; lactate dehydrogenase activity, oxidative stress markers (lipid peroxides, nitric oxide and reduced glutathione), inflammatory markers (myeloperoxidase, tumor necrosis factor-alpha, nuclear factor kappa-B, interleukin-6 and interleukin-10), apoptotic biomarkers (caspase 3 and cytochrome C), neurotransmitters (glutamate, gamma aminobutyric acid), Cys-LTs contents and CysLT1 receptor expression; as well as total brain infarct size and histopathological examination of the hippocampus were assessed. Montelukast protected hippocampal tissue by reducing oxidative stress, inflammatory and apoptotic markers. Furthermore, it reduced glutamate and lactate dehydrogenase activity as well as infarct size elevated by I/R. These results were consistent with the histopathological findings. Montelukast showed a neuroprotective effects through antioxidant, anti-inflammatory and antiapoptotic mechanisms.

Time course change of COX2-PGI2/TXA2 following global cerebral ischemia reperfusion injury in rat hippocampus.

BackgroundNeuroinflammation plays pivotal roles in the progression of cerebral ischemia injury. Prostaglandins (PGs) as the major inflammatory mediators in the brain participate in the pathophysiological processes of cerebral ischemia injury. Cyclooxygenase-2 (COX2) is the rate-limiting enzyme of PGs, and thus it is necessary to characterize of the expression patterns of COX2 and its downstream products at the same time in a cerebral ischemia/reperfusion (I/R) model.MethodsThe levels of prostacyclin (PGI2) and thromboxane (TXA2) and the expression of COX2 were detected in the rat hippocampus at different time points after reperfusion (30 min, 2 h, 6 h, 24 h, 48 h, 7 d, and 15 d).ResultsThe COX2 mRNA and protein expressions in hippocampus both remarkably increased at 30 min, and peaked at 7 d after global cerebral I/R compared with the sham-operated group. The level of PGI2 significantly increased at 2 h after reperfusion, with a peak at 48 h, but was still significantly higher than the sham-operated animals at 15 d. TXA2 level decreased at 30 min and 2 h after reperfusion, but significantly increased at 6 h and peaked at 48 h. PGI2/TXA2 ratio increased at 30 min after reperfusion, and peaked at 48 h compared with the sham-operated animals.ConclusionsI/R injury significantly increased the COX2 expression, PGI2 and TXA2 levels, and the PGI2/TXA2 ratio in rat hippocampus in a time-dependent manner. As a consequence, the increased PGI2 level and PGI2/TXA2 ratio may represent a physiological mechanism to protect the brain against the neuronal damage produced by I/R injury.

PPARα Agonist Fenofibrate Ameliorates Learning and Memory Deficits in Rats Following Global Cerebral Ischemia.

Increasing evidence demonstrates that local inflammation contributes to neuronal death following cerebral ischemia. Peroxisome proliferator-activated receptor α (PPARα) activation has been reported to exhibit many pharmacological effects including anti-inflammatory functions. The aim of this study was to investigate the neuroprotective effects of PPARα agonist fenofibrate on the behavioral dysfunction induced by global cerebral ischemia/reperfusion (GCI/R) injury in rats. The present study showed that fenofibrate treatment significantly reduced hippocampal neuronal death, and improved memory impairment and hippocampal neurogenesis after GCI/R. Fenofibrate administration also inhibited GCI/R-induced over-activation of microglia but not astrocytes and prevented up-regulations of pro-inflammatory mediators in hippocampus. Further study demonstrated that treatment with fenofibrate suppressed GCI/R-induced activations of P65 NF-κB and P38 MAPK. Our data suggest that the PPARα agonist fenofibrate can exert functional recovery of memory deficits and neuroprotective effect against GCI/R in rats via triggering of neurogenesis and anti-inflammatory effect mediated by inhibiting activation of P65 NF-κB and P38 MAPK in the hippocampus, which can contribute to improvement in neurological deficits.

Effect of mild hypothermia on expression of hippocampal microRNA-210 during global cerebral ischemia-reperfusion in rats

Objective To evaluate the effect of mild hypothermia on expression of hippocampal microRNA-210 (miR-210) during global cerebral ischemia-reperfusion (I/R) in rats.Methods Sixty healthy male Sprague-Dawley rats,aged 9-10 weeks,weighing 280-320g,were randomly divided into 3 groups (n =20 each):sham operation group (group S),group I/R,and mild hypothermia group (group H).Ventricular fibrillation (VF) was induced with transoesophageal cardiac pacing followed by cardiopulmonary resuscitation to establish the global cerebral I/R model.In group H,the rectal temperature was cooled down to 32-34 ℃ by rubbing body surface with ethanol within 10 min starting from onset of reperfusion and maintained at this level for 6 h.In the other groups,the rectal temperature was maintained at 36-37 ℃ with a heating blanket.Rats were sacrificed at 24 h of reperfusion,and then the bilateral hippocampi were removed for detection of miR-210 expression (using RT-PCR) and apoptosis (by TUNEL).Results Compared with group S,the expression of miR-210 was up-regulated,and apoptosis rate was increased in group I/R.Compared with group I/R,the expression of miR-210 was down-regulated,and apoptosis rate was decreased in group H.Conclusion Mild hypothermia playes a role in cerebral resuscitation possibly by down-regulating miR-210 expression and reducing apoptosis in hippocampal cells of rats. Key words: MicroRNAs; Hypothermia, induced; Brain; Reperfusion injury; Hippocampus